How Often Should I Service My Car?

Last Updated 22/03/2016

I’ve had discussions and read about service intervals a fair bit over the years. There’s a few different points of view. Some people service more frequently than the manufacturer’s recommendation. Some people service less frequently than the manufacturer’s recommendation. And of course some people service according to the book. Which is best? This article explains my point of view.

Reduced Service Intervals

Reduced service intervals means servicing more often than what is recommended by the manufacturer. The time between services is less. Some reasons to support this idea include:

– Extra servicing is a small incremental cost that can help extend the life of your vehicle. The cost is small compared to the cost of the repairs that you may be avoiding through frequent servicing. The old adage “cheap insurance” is often used to explain this idea.

– Modern vehicles are precision machines and need to be serviced regularly to maintain their precision. All the sophisticated electronics, sensors, instruments, mechanical components and emission controls are sensitive to less than ideal lubrication, dirty fuel, poor filtering, etc.

– Manufacturers don’t specify frequent enough servicing as they do not want to be perceived as being expensive to service. They want to be perceived as having low running costs. Fuel efficiency is obviously most important in terms of running costs, but so is reduced servicing costs.

Extended Service Intervals

Extended service intervals means servicing less often than what is recommended by the manufacturer. Some reasons to support this idea include:

– Manufacturers are conservative with their recommended service intervals. They want to over specifiy servicing to encourage indifferent people to service their cars frequently enough. If someone has an attitude of “I’ll stretch it a little bit, for as long as I think I can get away with it” then it’s better to stretch from an over-specified schedule to mininize damage. Manufacturers also want an easy way out of warranty claims if a vehicle hasn’t been serviced according to over specified intervals. They want to protect their reputation as being a reliable manufacturer so they recommend more frequent than necessary servicing. For the manufacturer, it’s cheap insurance, but to the end user it may be unnecessary insurance.

– Manufacturers make money through servicing, so they recommend more servicing than required.

– Modern cars burn clean. They need to burn clean to comply with emission standards. Modern fuel is clean. It needs to be to comply with fuel standards. So contaminants are much lower in new vehicles, which means lubricants and filters last much longer. Manufacturers have kept service intervals about the same without considering the changes in the modern era of motor transport. This means there’s room to extend service intervals on modern vehicles.

Cheap Insurance

You may have noticed I mentioned “cheap insurance” for both reducing service intervals and extending service intervals. That’s because I am making a point – the “cheap insurance” argument is not valid. Cheap insurance means small incremental costs are ok even if there is possibly no benefit, because the cost is small and there is still a chance of benefit. Consider how this applies to service intervals. If the manufacturer recommends an oil change every 10,000km, then an oil change every 8,000km would comply to the cheap insurance argument. Servicing only slightly more often doesn’t cost much more. What about, once you decide to change the oil every 8,000km, you discover that it’s now only a small incremental price increase to change the oil every 6,000km. What about 4,000km?  What about 2,000km? Do you see a problem here? Applying the “cheap insurance” argument as a general philosophy means, through many small increments, you now need to change your oil every day.  If the “cheap insurance” argument applies from 10,000km to 8,000km then it similarly applies to every other incremental service interval. Through cheap insurance, the accumulation of many small cost increases can continue indefinitely. Your servicing costs will approach infinity. How does one applying the cheap insurance argument pick 8,000km over 6,000km? How do you decide at what point to stop servicing more? The point where you don’t think it provides any extra benefit? In that case there is no cheap insurance arguement at all, the point is chosen based on benefits. If choosing a service interval based on benefits, then it invalidates the initial cheap insurance argument that a small increment in price is ok regardless of a potential lack of benefits.

The argument for servicing a vehicle more often, from say 10,000km to 8,000km, is exactly the same as the argument for extending the service interval from 10,000km to 12,000km. It’s a trade off between servicing costs and maximizing vehicle life. The trade-off works in both directions. “Saving money by extending vehicle life through more frequent servicing” is, in terms of logic, applying the same principle as “saving money by avoiding unnecessary servicing when it yields no benefit.” You could say servicing the vehicle less often is cheap insurance against unnecessary wasting of money on servicing costs. Even if applying the cheap insurance arguement in one direction (erroneously), you cannot apply it in a consistent fashion without servicing costs approaching infinity. It ends up being a decision based on perceived benefits. Any point can be deviated from in both directions using similar arguments. A philosophy that works, is to use all the information and experience at your disposal to pick a point that gives the lowest cost of ownership. This philosophy can be applied consistently and will give the best results. The same idea applies when considering to buy cheap no-brand stuff. The blanket cheap insurance argument isn’t valid. You need some sort of evidence or reasoning to make a decision with. Without that, cheap insurance eventually means you need to change your oil every day.

Who Knows Best

If you’re after advice on how often to service your vehicle, you need to watch out for people who have been swayed by isolated experiences. People who had something happen to them who then assume the same applies to all vehicles of that make and model. You also need to try to filter out people who don’t really understand the vehicle or how often it should be serviced or even the basic laws of physics. You want an expert who’s had exposure to as many of your vehicle’s make and model as possible. When looking for a source to guide you in your decision on service intervals, look for a source with the following characteristics:

– Has intimate knowledge of the vehicle’s design.

– Has experience with at least several thousand vehicles of your exact make and model.

– Has experience through the entire life cycle of your vehicle’s make and model, including design, manufacturing, servicing, repairs and warranty claims.

– Has thousands of accumulated man-hours of experience with your vehicle’s exact make and model.

Who complies with all these criteria? Not me! As far as I know, only one entity complies – the vehicle manufacturer. They are in the best position to gauge service intervals, so in my opinion you should service exactly according to your vehicle manufacturer’s recommendations. Not only is the manufacturer in the best position, but it is a perfect compromise between extended service intervals and reduced service intervals.

The problem with recommendations from mechanics, vehicle owners, or any other individuals, is that they are emotional and they are naturally inclined to take an experience and assume it applies to everything. You’ll hear things like “if you don’t service more often you’ll get sludge build up in the engine like I’ve seen in many vehicles in the workshop” or “if you don’t change your fuel filter often you’ll damage your injectors like what happened to me” or “when I change my oil it still looks clean so you can extend the service interval” or “I change my oil every 20,000km and my vehicle has lasted as long as anyone elses.” An individual’s sample set simply isn’t large enough to really know if the experience is isolated or common, even if the experience has been seen on multiple vehicles. How many of that vehicle have been sold in total? What proportion of vehicles are experiencing this problem? Will extra servicing actually resolve the problem? Is there any evidence that extra servicing definitely yields reduced probability of experiencing the problem? Is there a common source of mistreatment that is skewing the experience? Are there any local environmental factors that are skewing the experience? Does the mechanic providing advice have a personal preference for another brand of vehicle? Did the individual giving the advice have a bad experience with a warranty claim and now holds a grudge against the brand?

That’s not to say that the experiences, advice and recommendations from individuals don’t have any merit. A judgment needs to be made, but erring on the side of the manufacturer’s recommendation is usually pretty safe.

An Example – Diesel Fuel Filters

Modern diesel engines, like the one in my Hilux, have sensitive fuel delivery systems. They operate at high pressure, have many sensors and instruments and are metered with exacting precision. This means they are sensitive to fuel contamination. Many owners of diesel vehicles are replacing their fuel filters much more often than recommended by the manufacturer. Not just slightly more often, but in the order of 10 times more often. Ridiculously often. Is this justified or have they just fallen into the cheap insurance trap, incrementally reducing service interval times due to fear of fuel system damage without any evidence that it provides any benefits? Will it actually help protect sensitive diesel fuel delivery systems?

As filters age, they don’t filter less. They continue to filter adequately as they age. In fact they filter more as they age. New filters do not filter any better than old filters. A brand new filter will filter less than an old filter. A new filter is not going to help protect a vehicle’s fuel system from contamination.

As filters age, they do become blocked. They restrict flow. This manifests as a pressure drop across the filter. This flow restriction needs to be kept within certain limits. The manufacturer achieves this through either scheduled replacement of the filter, or through instruments which measure the condition of the filter. Usually the instrument will be some type of pressure sensor, measuring how much pressure drop occurs across the filter. When the pressure exceeds a certain setpoint level, a warning light comes on and the filter needs to be changed. The instruments measure pressure rather than flow. Flow will be maintained according to the requirements of the fuel delivery system. So to detect a flow restriction early, you cannot use flow. Pressure drop across the filter (back-pressure) is used to monitor the filter’s condition. It gives an early warning for flow restriction whilst the flow rate is still at correct levels.

You would have heard of filters that can be washed and re-used. These filters don’t lose filtering ability with age, they become blocked and need to be washed. Once washed, they are no longer blocked and will continue to filter adequately. This is a good example demonstrating the physics of filters. A filter that can be washed operates on exactly the same principle as a filter that is replaced, except the washable filter is mechanically designed so that the filter element can be properly accessed for washing and the filter element is designed to be strong enough to withstand the washing action. Apart from that, it’s just some sort of filtering medium like paper, the same as a disposable filter.

In industry, the lube systems of large equipment worth millions of dollars are protected by an instrument that measures pressure across a filter. When the pressure exceeds a setpoint level, a “filter blocked” alarm is raised on the control system for the machine, and the filter is replaced. The owners of these multi-million dollar machines do not bypass this strategy and replace the filter extraordinarily often in the hope that it will extend the service life of the machine. They know it doesn’t work. So both heavy industry and vehicle manufacturers are in agreeance – consistent with the fact that old filters filter adequately but need to be replaced as they become blocked.

Water will damage a modern diesel’s fuel system. Water is not filtered by any filter element, new or old. To separate water from fuel you need something that works on the differing density. Some fuel filters are housed in a bowl that is designed to trap water in the bottom due to water’s greater density than diesel. This process is not dependent on the filter element itself. A fuel filter element can trap suspended contaminants but it can’t filter out molecules of water. So we can disregard the water argument for replacing fuel filters more often. This is true for any other liquid contaminants that may be present in diesel – kerosene, ethanol, etc. A filter element will not filter out molecules of liquid.

So your fuel system is equally protected from fuel contamination and water with either an old or new fuel filter, and your fuel system is protected from excessive flow restriction through manufacturer recommended replacement intervals and / or instruments that measure the condition of the filter. Replacing your fuel filter more often does not improve filtering. If you’ve stuck with the manufacturer’s recommendation and you’ve had a fuel system failure, more frequent filter replacement wouldn’t have prevented it. Replacing your fuel filter more often increases the risk of contaminating the fuel system during the filter replacement process. In fact it’s guaranteed that you will be introducing contaminants into the fuel system when changing the fuel filter. There’s dust in the air, dust on the surfaces of the new fuel filter, dust and dirt covering the filter housing. It’s not possible to introduce exactly zero contaminants when changing a filter. If anything, you are increasing the risk of fuel system damage. At best you are unnecessarily spending money on something that yields no benefits. I worry that people are making it worse – that was one of my motivations for writing this article.

Based on my understanding of filters, the vehicle manufacturer’s service interval for fuel filters is correct. Those that replace more often are in conflict with the physics of filters. In fact always having a new filter may be allowing more contaminants through and increasing the risk of fuel system damage. The designed operating point of a filter is midway between being new and needing replacement. This is a stable area of operation, where the big holes of a brand new filter are plugged up but the resistance to flow is still low. This operating area is the right compromise between filtering ability and pressure drop according to the design.

For my model Hilux, there is no scheduled replacement of the fuel filter. According to the manual, you change it when the instruments that monitor its condition tell you to change it. Mind you the newer model hilux has a recommended replacement interval of 40k. Perhaps in my older model it should be changed according to the new schedule, or maybe Toyota just kept getting asked too many questions about not having a scheduled service interval so they thought it would be easier to put one in. Anyway I changed mine at 100,000km out of interest, to see how bad the filter looked and to not let it get too old. The inlet side was dark, the outlet was clean white. There was no sludge or thick coating on the filter. The inlet side felt clean but the colour was dark grey. The bottom of the canister was clean apart from some metallic specks. Those specks would just stay in the bottom of the canister forever without effecting anything. Looking at a used filter it not really relevant – the condition of a filter should be judged by its resistance to flow, not its appearance. The instruments that monitor my fuel filter were reporting that the filter was ok after 100,000km.

hilux fuel filter after 100,000km

Some people change the filter in their hilux every 5k. That’s 20 times more often than me. For a filter worth about $30 over a vehicle life of say 300k, that’s $1800 worth of filter vs $90 when replacing every 100k – an additional cost of $1710. That much money will buy you a couple of new injectors. What if we include labour? Time isn’t worthless, even if doing it yourself. It means less time to do the things you want to do. It means being closer to your death without having done those things. Let’s put a value of time at $50 per hour. Thats cheap – my time is worth double on weekends because I’d rather be fishing then servicing a car. If it takes half an hour to replace the filter that’s $25 in labour per filter change. Over the life of the vehicle that’s $1500 when replacing every 5k compared to $75 every 100k. Total cost of fuel filters when replacing every 5k is $3300 compared to $165 replacing every 100k – an additional cost of $3135. That will probably do you a complete set of new injectors. Not only do the costs accumulate to a significant amount over time, but it provides no benefits. Actually it increases the risk of contamination of the fuel system as explained above. Is that cheap insurance or false economy? Imagine how the costs accumulate if applying the cheap insurance idea to all the other servicable items in a vehicle.

Some people are upset when the filter light illuminates in their Hilux or similarly designed vehicle. They’re upset because they believe the filter should have been replaced according to a more frequent scheduled replacement before the filter light came on. Actually the filter light coming on is exactly how the system is designed to operate. The filter is still filtering perfectly well when the filter light comes on. The engine is perfectly protected. There is a flow restriction, but not enough of a restriction to effect fuel delivery. The instrument that generates the filter light measures the back-pressure across the filter as a means of early detection of a flow restriction. Flow rate is still ok. The pressure setpoint for the filter light is chosen to give you time to replace the filter. Get it done in the next few weeks, at your earliest convenience. This is the same as how industrial equipment is protected from blocked filters. The blocked filter alarm on an industrial machine is a warning only. The machine can still operate but it tells the operators that they must replace the filter at the next convenient time as the back pressure across the filter is becoming too much. Flow is still ok. Leave it for a few months and it’s likely the flow restriction will become so large that some other protective device will operate and prevent the machine from running.

The fuel filter example is typical of what occurs when deviating from manufacturer’s recommendations. It reinforces the idea that vehicle manufacturers are in the best position to gauge service intervals. Still, it’s personal choice on how often you service your vehicle. The manufacturer’s recommendation is a guide, and everyone has the right to choose as they please based on their own experiences and understanding. The odds are that the manufacturer’s recommendations are on average pretty good, but the manufacturer isn’t perfect and there may be isolated cases where deviating is a valid position to take.

See also:

Do You Need a Suspension Lift Kit?

Emission Systems – Worth Tinkering?

How to Improve Fuel Efficiency

How Failure Works

Diesel vs Petrol

Why No Diesel Performance Chip?

back to 4WD, Touring and Camping

more articles by outbackjoe

28 replies »

  1. Just been stung $1600 for a service on my Pajero. Non standard work consisted of skimming the brake disks as they had become pitted from driving on the beach. I am now out of warranty on my NS so considering extending my service intervals.

    I have had oil analysis recommended to me as a way of extending your servicing intervals safely. Do you have any thoughts on this?

    • Yeah oil analysis allows you to replace oil only when actually needed so may be a safe way to extend oil change intervals, but I have no experience with it so don’t know how expensive it is or how much you save compared to servicing according to manufacturers recommendation. Everything else you would still service according to manufacturer unless you have a way of measuring their condition also.

  2. Very well. For me is not clear, what about filter and oil quality. Some manufacturers have same service interval, independently of used oil (mineral, semi-synthetic or synthetic, and which quality of them, because I am sure that there are big differences in quality on market – as in price, too).
    According with:
    maybe is better idea, instead often servicing, invest in better quality of service parts?

    • Hey Dusko if you use an oil that meets the vehicle manufacturer’s specification and the oil is of at least average quality then I think you will be fine using the manufacturer’s service interval. You get variations between different oils but it doesn’t matter much I don’t think. When the service is due the oil is still lubricating pretty good. So a little bit more or less than pretty good is still pretty good. The oil doesn’t suddenly turn bad and destroy the engine. Maybe if you use expensive oil and want to extend service intervals it might be worth getting oil analysis done. Short of that I think you are pretty safe using the vehicle manufacturer’s service interval.

      I’m not sure about the claims made in the article you refer to. If there was a cheap and easy way to halve engine wear then for certain it would be exploited by vehicle manufacturers. Otherwise you may well be an upcoming millionaire if you have a cheap and easy way to double everyone’s engine life. Reduce wear by 70%? Industrial equipment worth millions of dollars a piece like haul trucks and massive diesel gensets can be made to last over 3 times as long by putting in a better filter? May I suggest billionaire?

  3. Hi Dusko, if you are interested in tweaking your service intervals or if you are simply interested in the rate of wear in your engine as compared to similar engines why not grab yourself a free sampling kit with prepaid mailing pack from the cost of the laboratory report and recommendations is 39.50 and only payable once the analysis has been performed.

  4. Toyota recommends 5000km oil change intervals (read the owners manual under what is “normal conditions”).
    Mitsubishi is 7500km , and i strongly recommend you stay with it . normal conditions are every time you drive you don’t do highway or stop start driving and do at least a 30 min run , or tow or drive in dust or mud . that puts everyone into 5000km intervals . have you factored the loss of resale value your car will have due to having been poorly serviced ? oil is cheap . (compared to engine damage) .
    your fuel filter is critical and they cheap insurance , some mines change fuel filters every oil change (5000km as per manual) due to conditions . how often should i change them ? if the light come on it is a water light , drain filter and monitor . if it happens again , pull it out and check . i have a spare filter in a housing (get one from a wrecker) with a fuel line looped over the fittings to keep it clean . 05/6 fuel filters were 90km (From memory) .
    hiluxs have a computer controlled alternator (as do most cars these days) and have a slightly lower voltage , which is why duel battery systems “need” a battery charger for the second battery . or , you can get a fuse from eBay that simply replaces the original and gives you about 0.5-1.0 volts more . by the way under no circumstances use a reusable foam or K&N style of air filter , hot wire air mass sensors hate them so do rings . lift your air filter lid and wipe your finger inside the hose , any dust ? don’t wash air filters , filters are oil impregnated paper , some manufactures don’t recommend cleaning . the dust “sucks” the oil out of the paper thus rendering the filter ineffective . keep your AMS clean with co contact clean or AMS cleaner . oil , synthetic oil is usually only necessary if you have a particulate filter (usually only auto turbo diesels have them , but check) then you require an ACEA-xx rated oil to suit .
    is an auto locking diff legal in the front ? id have to check . will it affect the steering adversely ?
    i got more , exhaust , one thing id have to say you are wrong about is exhausts , large diametor exhaust do the opposite to what you say , (this is only turbo diesel) the biggest gain is bellow 2000rpm due to allowing the turbo to boost earlier ( go to any dyno shop and ask for anyone’s before n after runs) plus they will reduce EGT’s (gas flowing into an increasing diameter will slow in velocity and cool)
    this is how alot of dyno shops claim to not harm your engine ,factory EGT’s are maintained .
    anyway love the blog , i hope to do a trip similar one day .

    • Hey Warren

      Sounds like you didn’t read a lot of the articles properly.

      For certain, Toyota recommends 10,000km service interval for the hilux for normal conditions. I read the manual every time I service because I service exactly according to the manual. Actually the whole point of the article is to be consistent with the manufacturer’s recommendation. Most new cars are every 10,000km regardless of fuel type.

      There is no such thing as cheap insurance. It’s explained in the article. I very much doubt they change fuel filters every 5,000km in mining. It provides no benefit, only extra risk and expense. Fleet operators would know better. I know that in mining, on equipment worth millions of dollars, they change filters when the instrument that monitors the filter’s condition indicates that a new filter is required. The fuel light on a hilux has two modes – one to indicate it’s time to change the filter, the other to indicate there is water in the filter housing.

      Yes hilux alternator is regulated by some electronics. It’s irrelevant. The output is 13.8V which is exactly what most lead acid battery manufacturers specify for float charge. No DC-DC charger is needed, and a DC-DC charger has many disadvantages. It’s not a fuse, it’s a diode that you get from eBay to boost the voltage. Permanently holding lead acid batteries at elevated voltage causes premature failure. It should not be done. All intelligent chargers only boost the voltage whilst the battery is sinking a significant current. As the battery approaches full charge the voltage is reduced back to float level. Diodes permanently hold the voltage at an elevated level regardless of state of charge. This is completely explained in the article here:

      For certain, larger exhausts reduce low level torque and worsen fuel economy. I’ve seen the dyno runs. At low exhaust volumes a smaller exhaust pipe is making it easier for the turbo to spool since the higher gas velocity is creating a low pressure area after the turbo. It’s all explained in the article here:

      I’ve seen lot’s of discussion about EGTs and exhaust size. It’s all speculation. I’ve not seen any formal testing. According to your theory, at low engine rpm a smaller exhaust will provide lower EGTs, since the smaller exhaust creates a lower pressure at the exhaust manifold compared to a larger exhaust. The cooling of gas nothing to do with flow velocity and everything to do with pressure drop. See under cooling section. The smaller exhaust drops the pressure more so the exhaust gas will cool more. In reality I don’t think exhaust size makes much difference to EGTs, it’s just something that people who make money from selling exhausts promote and people who have larger exhausts like to confirm to justify it. The area of exhaust gas that is most relevant to engine health is between exhaust valve and the turbo, before the exhaust pipe. Much of the benefits people see when installing a larger exhaust can be attributed to confirmation bias:

  5. hi Joe , go and get your Toyota warranty and service book first ……… turn to section 2 under additional service requirements . found it ?
    “how and where you drive your Toyota determines the service requirements as much as the time or distance traveled . for example if you are regularly towing heavy loads , (you are ) driving in rough conditions (you are) or simply performing lots of stop start driving then more regular maintenance is necessary . discuss the typical sort of driving you’ll be doing with your Toyota service advisor , they will advise how best to maintain your vehicle to keep it performing at its best.
    if you consistently put your vehicle through extreme conditions or drive in harsh environments , then your vehicle ill require the extra maintenance as described i additional service schedule .”
    quote from hilux warranty and service book .
    so Toyota DOES recommend 5000km services . all manufactures will have similar disclaimers , i don’t know how anyone can drive a car without falling into “harsh driving conditions” . theis , extrata ,orica and i think bis all change their fuel filters at 5000km , it is common practice , down time is worth more than the filter by a 1000% . (this is mine sites only , you’re a hard rock man ? coal is much harder on cars ).
    how can the automotive aftermarket industry have it so wrong about exhaust mods ? can the entire industry be a con ? no , EGT will be reduced by a dump pipe and larger system (than standard), the pressure differential will “pull” (due to the lower back preasue) the gas out , this is very well documented . now the aftermarket chips exploit this and then put more fuel in thus raising EGT back to factory levels . watch the v8 super cars , do they have std exhausts ? any motor racing ? no .
    man i havnt done this typing for a while , anyway where you of to next ?

    • Hey Warren your previous post referred to normal conditions which is 10,000km. I service according to that. I don’t tow, don’t do short trips and drive economically. Fuel use is a good indicator of engine loading and my fuel use is around 10l/100km. Most people I think would come under normal use unless they always do short trips or tow something big. But you are right that if you conform to the manufacturers defined heavy duty then you should service accordingly.

      The point of the article is that people should service according to the manufacturer’s specification. My personal application of my vehicle use is just an example. I’m not saying everyone should service their vehicle every 10,000km. I am saying follow the manual.

      Some people believe manufacturers are conservative and you should extend service intervals. I think staying in the middle is a pretty safe bet. Old filters filter better than new filters. Replacing a filter more often does not reduce the risk of contaminant damage. Actually it increases it. Old filters need to be replaced due to flow restriction not because they do not filter adequately. Do you have a reference for mining companies changing the filter so often in vehicles? Are you sure it’s not just normal service every 5,000km and replace fuel filter less often? That would make sense since the short trips puttering around the plant and extreme environment would conform to manufacturers heavy duty service interval but the manufacturer does not call for more frequent fuel filter changing. If they do replace fuel filter every 5,000km it is inconsistent with the way they service filters in all other equipment. In other equipment they leave a filter in until it presents a high restriction to flow. I know this because I write the software that raises the maintenance alarm based on the instrument that monitors the filter. Hilux has a similar instrument which is why I say it’s strange that mining companies would be inconsistent with their maintenance philosophy and contrary to filter physics. You ask how can after market vendors have it wrong. Similarly how can vehicle manufacturers have it wrong? Vehicle manufacturers try to sell you something according to unambiguous, public and verifiable specifications. After market vendors just try to sell you something. They are missing the second bit. Claims like “lower egts” or “super cool egts” can be made without specifying the minimum number of degrees that the system is guaranteed to provide and without any verification. The customer gets the system and happily drives away with super cool egts. Not that I think everything aftermarket is crap. I mean my default position is to be cautious about claims. Why don’t vehicles come out of the factory with larger exhausts given the extra cost of a bit of extra metal is negligible once integrated into mass production? All designs have compromises including exhaust pipe design. Bigger isn’t universally better. That’s the purpose of the article. Bigger is better only at high exhaust volumes. If you add a chip then you dump more fuel in the engine and a bigger exhaust may help due to higher exhaust volume. I state that in the article. Still I’m not sure if it helps with egts I have never seen anything but speculation. We are back in Brisbane cleaning up the car and off to America in a couple of days. Hilux will be sitting in the garage until January and then we track down the east coast of oz.

  6. I changed all the fluids and filters when I bought my Delica simply because it was used and is a 15 year old vehicle. I had no log books or service history, so I decided it would be better to just replace as much as I could with high quality filters and fluids/oils as preventative maintenance. The oil and oil filter is recommended to be changed approximately every 5,000km on these vehicles as they the 4M40 engine is quite sooty.

    However some owners change less frequently, say every 7,000 or 8,000km, and have not reported any adverse effects as of yet. I understand the point you made about “cheap insurance” but for me it’s more of peace of mind as doing an oil and oil filter change is pretty easy, quick and cheap to do and can potentially save some major headaches in the long run. I would definitely not be changing the fuel filter as frequently though.. every 5k is insane! The recommended interval for the fuel filter in the diesel Delica is about 40,000km from memory.

    • Yeah fuel filter every 5k is crazy. More servicing = more better isn’t necessarily true. Replacing everything of unknown history is a good idea I reckon. Your manufacturer quoted 5k for a reason so aligning with that is the way to go.

  7. Just found this article as topical for me presently. I’m on the fence, but point taken on the manufacturer having a “good base” of data to assess best time interval. Cheers

    • Yo Baz I’m worried if you don’t over service your landrover then when it breaks down you’ll blame the lack of servicing. Actually it would have broken down anyway! Just kidding, good luck!

      • Good point, although I now have a Toyota 79 series Dual Cab…

        I have read quite a lot of other research suggesting frequent filter changes is the way to go. I understand some of the arguments for not changing, after all if it isn’t constricted why change.

        I suspect part of the issue is that we have no real control over fuel “hygiene”.


      • Ahh upgraded, nice work, good one. Hows the fuel consumption compared to landrovers? New filters don’t filter any better than old ones but with the probs we’ve seen with common rail diesels and fuel quality I guess people want to do something about it.

  8. Hey Joe,

    Excellent blog. I have a question but it’s a bit off topic. You can delete this post and email me direct if you wish.

    Just got myself a secondhand landcruiser and I want to know if you use any sort of underbody sealer/rust preventative on your 4wds? If so what do you think works the best.

    I’ve had mx bikes, which I used to just dose heavily with wd40 after a good wash. This worked pretty good for them.


    • Hey Kevin I use Lanolin. It works really well. It adheres quite strongly and does not wash away easily. This dude on the hilux forum tested all these bits of metal with various rust inhibitors and lanolin came out on top. It’s good stuff. There’s a couple of brands I know of – lanox and lanotec. I dunno if one is better than the other, I’ve used both. Spray it everywhere and if you can don’t drive for a few days so it loses some of its stickiness so it wont attract too much dirt and sand.

  9. Honestly. the information that I’ve gathered on these topics is pretty straight forward > Manufacturers of vehicles have 2 VERY pressing issues:
    1 – Meet emission standards
    2 – Sell cars – which usually also involves making them better / more powerful than the older unit whilst still meeting emission standards….

    Take for instance engine Oil Weight / viscosity. In many instances, vehicle manufacturers are going lighter and lighter as the reduced viscosity results in lower parasitic load, better efficiency and emissions. So, they decide that the end user should use 0W20 (purely for example only) knowing full well that a 0W30 or 5W30 would give better NET engine life…

    Cars (and their service schedules) really aren’t built around making them last 200,000kms + any longer… My advice is that if you want them to last longer, then you best start taking preventative measures that differ from blindly following a handbook.

    My 0.02 anyway
    *these points raised above are not aimed at any specific vehicle or manufacturer and is our experience across the entire industry ‘trends’

    • Hey Matt yeah its all on a spectrum. The manufacturers also have reputations for reliability to protect, which helps them sell more cars. If there were easy runs to be made on the servicing side of things to improve engine life I reckon the manufacturers would take it, in order to be able to sell more cars in the future through improved reputation. For example they might take a hit on the oil specification knowing that the impact to engine life is relatively small, especially since many people use their vehicle for short trips where the engine oil is already too thick. Actually I read an article on some guy saying we should use oils thinner than the manufacturer specifies because on average, for typical western middle class applications, the manufacturer specified oil is too thick, coz most people use their cars for short trips.

      If you aren’t blindly following a handbook, what are you following? Blindly following some guy’s story on “cheap insurance”? What about the dudes that believe in extended service intervals? Where does their research come from? Probably a similar source to yours. Industry experience. Recognizing trends. Etc. You can make up stories either way. A pretty reasonable compromise is to follow manufacturers recommendations. I wouldn’t call it blindly following. I’d call it educatedly following.

      The idea of changing a fuel filter more often than specified is very common. How well founded is that, given my explanation on how old filters filter better than new ones and how owners of multi million dollar equipment approach filter changes?

      I got oil analysis done on my oil at 10,000km. The technician said I should extend my oil change intervals by at least 2,000km. This is based on laboratory results. Surely laboratory results are better than stories of cheap insurance?

      You mentioned in a comment on the chip article that engines are over-engineered, suggesting that chips can be installed whilst still having good reliability. But now engines are running so close to the limit that we need to service more often just to get a reasonable life, even though simultaneously the engine is over-engineered so that it can have reasonable life with a chip installed?

  10. Hi Joe – I like your logical approach. After 32 years (bought new in 1985) & almost 600,000km trouble free driving my Daihatsu Rocky 2.8 Turbo was T boned by a young 4×4 driver on a dirt road west of Mittagong. Always did my own maintenance & servicing ” according to the book” using good quality materials. The only upgrades she got were – when new, a full underbody/cavity seal using Tectyl 506 (by me) and a larger bore, straight through, exhaust (after the factory unit disintegrated at about 400,000k) sounded great! – no other discernible benefit At about every 100,000 a new set of 4 Monaro HD shocks which always improved handling. Oh I did put a very strong magnet, I had found, on the outside of the oil filter and used a diesel fuel conditioner about once per service interval (5,000k) – made me feel good. Rocky was a great little tug regularly pulling a double horse float with two 550kg horses on board. Never had good brakes from new but my family & I drove accordingly.
    Now “upgraded” to a Ranger XLS 6 speed manual and having service withdrawal symptoms.
    Would be interested in your thoughts on the fitting of an “oil catch can” to the engine breather/air intake system to prevent oil contamination of air inlet sensors (Rocky breather just went to atmosphere.)

    • Hey Sean nice 600k and would still be going. Yeah catch can is helpful I reckon. I got one. Might help slow down soot accumulation. But then I think the problem of soot accumulation is exaggerated by those who need to justify tinkering. Catch can is reasonable accessory but not compulsory.

      • Hey Joe! I thought that the information contained in concerning catch cans was rather good. I particularly liked the following advice from that article that echoed your own previous statements concerning over-servicing and engine tinkering in general :
        “We checked with a development engineer from General Motors about the need for catch cans on non-competition vehicles and he told me that if GM believed for one second that a relatively cheap part attached to the engine would improve reliability, limit warranty claims and reduce replacement costs, it would have been included in the PCV system”
        I always enjoy reading the stuff on your site. I was considering getting a catch can and after reading your article and having a bit of a think – I won’t. Thanks again.

  11. Hey Joe, just found your site, love it, your thinking makes a lot of sense to me. In relation to service intervals what is your thinking about servicing according to time interval – even though the ks interval not reached – or servicing by kilometers.

  12. I read the below article recently, which adds some data to the arguments.
    What i also liked in this article was some of the common sense (which is by definition – not that common) about how to treat your car to help it do it’s job.
    Further, it talks about the idea of testing your oils, something i’m currently investing as a further “diagnostic” of engine health.
    In truth, manufacturers only really get to set simple standards, and therefore it’s up to the more informed drivers/owners to make better decisions about maintenance.
    Manufacturers set simple standards based on the principle of the continuous curve, law of diminishing returns – the more push something the longer it lasts. Even then they give more detailed advice, that nobody reads anyway.
    I wonder why don’t people “de-tune” vehicles i wonder? They would last even longer… 😉
    Anyways, have enjoyed and respected your comments, and “balanced” arguments.

  13. I bought a 2012 Kia Sorento running on 4 cyl Diesel 2.2.

    My mechanic was telling me today that i should do oil change every 5,000 km because my car has done 253,000km of age.

    Based on this article and what my car dealership told me over the phone, it is OK to have the oil change done every 10 to 15k as recommended by owners manual/manufacturer?

    Should i do oil change every 5k or 10k or 15k? Given the age of the engine so far. The manufacturer recommended interval is 15k.

    Based on this article can someone provide for me a humble opinion or recommendation?

    Same goes for my gearbox. Every 40k oil change? Dealership tells me it never needs oil change ever. Some mechanics tell me every 100k oil change for transmission if using fully synthetic.

    • Hi Imtiaz did the mechanic explain why the oil should be changed more frequently? Does the engine make more soot than normal or something?

      If you do mainly long trips and you’re gentle with the engine when it’s cold I’d be more inclined to go with the manufacturer’s recommendation. If you do short trips then replace more often.

      You could get oil analysis done at 10k or so. See if you should go more or less from there.

      If the manufacturer says the gearbox oil is for life then I’d probably change it every 150,000km or something. Pick a big number. I think the oil for life thing was a bad idea that some manufacturers got from lab data and short vehicle turnovers that doesn’t translate well to real world. But if they think good for life it should be good for quite a while.

Leave a Reply to Matthias Cancel reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.