All engine faults/repairs/maintenance Oils recommended

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This page put together by CovKid and California Dreamin - both with years of professional experience servicing VW's.

Now, you're either browsing the WIKI because you're curious as to "what oil" you should use, or more likely, you've been sent here because you're the six millionth person that has asked "What oil?"

Engine oil has perhaps been the most talked about subject on 80/90 - frequently the most neglected and often the least understood aspect of servicing and maintenance. Worse, the choices made are sometimes based on little more than myth, and threads frequently surface arguing the case for one oil over another, so we've decided to create a more extended and detailed WIKI section for engine oil with answers to the most common questions. California Dreaming is a time-served VW engineer and Covkid has worked on VWs for some 25 years including building race-spec VW engines but whilst we both came from different ends of the business, remarkably we both agree on the information provided here.

This page is for stock engines found in the T25 range and the recommended grades for each although the information also applies to the T25's ancestors - the Type 1 (bug) and Type 2 (bay/splitty). We do not recommend 'makes' of oil as that is not actually of much relevance - nor should you pester other 80/90 members to find out what they use. Everything you need to know is here - make your own choice as to brand. If you just need a quick answer without too much brainstorming, skip down to the Petrol or Diesel sections and the suggested grades are there!

Firstly, reading through should give you a greater appreciation of the role of your oil, what may or may not work for your engine, and whether paying more, delivers more. We do recommend you read right through. There are additional links for those that want to explore beyond the content provided here. Alternative engines, Subarus, V12's whatever, fall outside the remit of this section. In such instances you should consult the manufacturers recommendations for that particular engine. Additional links are provided for anyone who has time to kill and for reasons we have no wish to know, want to explore the world of 'oil' in more depth.

Oil And What It Does

Engine oil actually serves a few purposes beyond lubrication. Oil also cleans, inhibits corrosion, seals and cools an engine. Oil has to work fairly hard and in varying temperatures, particularly with the aircooled engines which in most cases was devoid of a modern oil filter and tends to run hotter. Many modern oils have been developed to help meet the need for lower emissions as engine oil tends to make its way into combustion areas.


Firstly there is no 'right' or even 'perfect' oil but the recommendations below are sound and based on years of experience. Engine oil is always being developed and even 80/90 members disagree, some preferring monograde (though why escapes us), some using cheap or expensive multigrade (multigrade being versatile and able to cope with a wide range of conditions), and even "Fantabidosa premium brand with added mystery thingy". It is worth noting that CovKid rarely pays more than £10 for five litres (2011 prices) and generally gets his oil from places like LIDL or ALDI when they have it in as it far exceeds that required by the T25 - read the label. Spending £40 on oil is akin to those who buy premium unleaded fuel in the belief that they are somehow spoiling their engine. Oil manufacturers notoriously play on this kind of guilt so don't be guided exclusively by slick marketing. You are not driving a Ferrari.

However, one thing we both agree on is no matter what oil you use - change it regularly. Regular oil changes extend the life of your engine significantly and keeping the oil clean and topped up matters far more than how much you actually spend on it. The VW engine isn't doing the high revolutions of most modern performance-orientated cars so will run quite happily on a budget brand (within reason) providing you change it regularly. Engine oil generally has a shelf life of around 3 years.

Many modern oils (read the label) are formulated to work in both petrol or diesel but we recommend in the case of diesel, you should choose one specifically formulated for diesel engines rather than a dual-type.

How Often Should I Change My Oil?

Well, it depends. The flat four aircooled engine needed changing (ideally) every 3000 miles but as well as running at a higher temperature compared to the watercooled. The oil change frequency was therefore extended slightly on later engines. CovKid drives a watercooled 1.9DG petrol and covers around 12k miles a year, changing the oil twice a year. However, if for any reason it looks black or somewhat thin, you should bring the oil change forward. The recommended minimum for oil changes is every 6,000 miles or six months - whichever comes sooner.

Numbers - What Do They Mean?

Oil grades are numbered. Heres a brief explanation of what it all means.

Firstly, old-fashioned monograde (which is what it is - one grade) can thin at higher temperatures and generally, does not offer anywhere near the protection of most modern multigrade oils, designed as they are to perform at a larger operating temperature range. Even some of the cheaper multigrade is at least comparable with that recommended by VW in 1980-1990 and certainly before that. There are purists, particularly amongst bug owners who only use monograde, but these days, the advantages afforded by a good multigrade would seem to far outweigh any puritanical view that monograde is the right, or even only oil one should use. In 1938 perhaps (the birth year of the T25's ancestor), but even the humble beetle now has to keep up with the stop-start fury of modern traffic. Besides, it makes more sense to use an oil that can perform reliably and consistently throughout the year, from a freezing cold start to a baking hot day at high speed. Clearly there is a marked difference in temperature between starting an engine on a cold winters morning and an hour later hammering down the MI.

This difference in operating temperatures of engines, spawned the development of multigrade oils and removed the high demand for various specific grades, resulting in a largely 'one size fits all' approach to engine oils. Basically, multigrade engine oil numbers denote the cold and hot viscosity either side of the 'W' so 15W40 oil would perform like a 15 rated oil from cold and like a 40 when hot.

Straight forward explanation of the two numbers that make up an engine oil designation:

First number represents the thickness/weight (viscosity) of the oil at 0 degrees F Second number represents the thickness/weight (viscosity) at 210 degrees F The designation compares the oils behavior to how different weight 'monogrades' would behave under the same tests. So: 15W40 At 0 degrees F this oil behaves like a 15 weight 'monograde oil' And at 210 degrees F the same oil behaves like a 40 weight 'monograde oil' at the same temperature.

Hence why 'modern oils' are classed as 'Multigrades' (one oil that behaves like two viscosity's)

The actual measurement was originally designed by the Society of Automotive Engineers (SAE for short) the machine they used was called a (Redwood Viscometer) This device used a pre-set sized hole by which the 'rate of flow' of the oil was measured at the two temperatures mentioned above.

W was just a designation that was given to all mutigrades to signify their suitability for Winter use (bearing in mind that up until their introduction users were faced with twice yearly oil changes using basic monograde products).


Following from that, a 10W40 would perform like a 10 rated oil from cold but some owners (including us) consider it too thin for the VW flat 4 engines because of their particular habit (in some cases) of draining tappets when stood, although in exceedingly low temperatures more familiar to Eskimos, a low rating of 10 would be advantageous if you need to be up and about to trap seals. You get the picture.

Mineral oil is commonly used in T25s. So why not synthetic? Well some do use synthetic oil, which generally has better heat transfer qualities and theoretically works well in aircooled engines which can see elevated head temperatures, but only if you have an oil filtration system (similar to those on watercooled engines instead of a simple oil strainer), otherwise the oil will become contaminated much more quickly and the additional cost possibly not justified. The other downside, and worth noting before you rush out and buy synthetic oil, is that it will find the tiniest leak and you could end up with oil spots all over your driveway. We're not ruling out synthetic and you may wish to go that route but if your engine is a bit of an 'oiler' the problem may well be made much worse with synthetic. However, for well maintained oil tight examples synthetic may work well as long as your particular engine doesn't suffer from tappet drain as many do. It is possible to find grades as wide as 5W50 in synthetics. Synthetics have evolved with engine development and the need for lower emissions these days. The price is generally higher for synthetics.

Do NOT mix mineral and synthetic as it could seriously reduce the capacity of the oil to do its job, and at worst render it useless.

SAE denotes that the oil is graded as per that specified by the Society of Automotive Engineers (a benchmark basically) and API denotes the quality of the oil, confirming that it meets certain specifications. More on API can be found in the great Engine Oil Bible (see footer links)

Oil Types And Other Thoughts

Increasingly modern oils seem to come in wider ranges and although 15W/40 is getting a little harder to find locally it is still readily available to order. 20W50 (at a pinch) would also be fine but perhaps climate change with sometimes excessively cold winters may preclude 20W50. I do know of owners that use 20W50 in the Summer and 15W40 in the winters and other combinations. Likewise, a diesel oil (which tends to have more detergents) could also be used - more so these days as the gap between diesel engine oil and petrol narrows. I ran a bug on Shell Rimula diesel oil throughout its entire life with no ill effects. In any event, if that was all the garage had in stock on Sunday morning, I wouldn't turn my nose up but certainly the recommended grade is 15W40 multigrade and the vast majority of T25 owners seem to prefer or opt for mineral rather than synthetic.


You can find good quality oil that meets and more often than not, exceeds VW T25 original spec from some supermarket outlets these days (LIDL for instance) and often, petrol forecourts have limited offers on engine oil. As has been pointed out by other 80/90 members, cheap oils can be absolutely fine but oil is an expensive commodity and they are not, or rarely, premium fandango brands disguised in a budget container. By the same token, it does not follow that spending £40 on a can of oil promising the earth is going to be far superior in a T25 than the can you saw priced at £15 either. The VW flat four is a fairly low-revving engine and an oil better suited to a high-revving race engine is probably wasted on the VW engine even if it makes the owner feel better. It would however be wise to steer clear of containers that provide very little information at all, but certainly don't rule out an oil simply because it is cheap or assume that the more it costs, the longer your engine will last or the faster it will go. Read the label, and if it seems reasonably good, go by your instincts.

As mentioned earlier, the concensus on 80/90 is that good old fashioned mineral oil is the safest choice, particularly if the engine has done many miles. Mineral oils are, as the name implies, based on oil extracted from beneath our feet, and refined. Synthetic oil (you could see it as a 'designer' oil if you like) is manufactured from various chemicals, although by and large, most of the ingredients do in fact derive from mineral based oil products. The molecular particles are much more even with synthetic oil which is why (technically) it has better heat transfer properties but as noted above, some have experienced minor oil leaks on both water and aircooled VW engines with synthetic oil, only cured by going back to mineral. The other type is semi-synthetic - a mix of the two. Further links are provided in the footer if you wish to explore synthetic and semi-synthetic oils in more depth. Note* 15W40 can be found as a semi synthetic and could be a good choice for those wanting the added protection offered without going down the 'thinner oil' route that may bring on the noisy 'tappet syndrome' that these engines occasionally suffer from, although perhaps to be avoided if yours already marks it's territory lol. You may get on fine with synthetic, but note the remarks on the potential for oil leaks. Some have no issues with leaks, some do. Its your engine, your choice.


1.9, 2.1, 2.0 etc:

Contrary to URBAN MYTH monograde oils are not the best for aircooled variants and were never used by volkswagen dealerships when servicing T25's/T3.

The specified oil recommended is SAE 15W/40 multigrade Mineral for petrol engines (although VW's service chart does show several variations dependant upon climate) - You won't go far wrong sticking to that. 15W50 would also be a good choice - particularly for aircooled engines which can run hotter. Change every six months or 6,000 miles MAX - whichever comes sooner.

One aircooled owner recommended 20W50 on the basis that 15W40 is more likely to seep past gaskets but we have no scientific evidence to back this one up at all and any seepage could simply be down to the quality/brand of the oil rather than grade and indeed symptoms of an old engine. I've only added this as the question came up in a thread.

Be warned: using a thinner oil in these engines (10W40 for example) can result in 'Noisey Tappet Syndrome' where the hydrailic tappet adjusters drain off when standing, resulting in horrendously noisey/rattley engine for the first 15 minutes of driving which certainly doesn't do anything for your campervan KUDOS lol. This issue doesn't occur to all engines but if you are running thinner grades and you do begin to suffer regular tappet clatter it would be a safe bet to revert back to a heavier grade as recommended above.


California Dreamin

Diesel Engined variants ALL: 1.6/1.6TD/1.7 & 1.9D/TD modified

This is another TOPIC FOR DEBATE as almost all 'normal' engine oils state on their labeling, quote: (ALSO SUITABLE FOR DIESEL AND TURBO DIESEL ENGINES) whilst these oils will perform adequately the WIKI is about recommending the most suitable products so that means buying an oil that is 'primarily' for Diesel engines.

Quote directly from the MILLERS OILS website Simply asks the question

Do I need different oil for a diesel and petrol engine?

Their Reply: Generally the answer is yes for older vehicles, as diesel engine oils have higher detergency levels.

This is an extract from an article explaining some of the differences in requirements of Diesel Engines:

Very simply the three main areas are: Higher dispersancy to deal with higher levels of soot Higher detergency levels to minimise depositing on components and as a result a higher TBN which will minimise the risk of Sulphuric Acid formation from diesel dilution. Another quote: Yet another crucial difference between petrol and diesel engine oils is that diesel engine oil has more additives per volume. The most prevalent are overbase detergent additives. This additive has numerous roles, but the main ones are to neutralize acids and clean. Diesel engines generate a great deal more soot and combustion byproducts. Through blow-by, these find their way into the crankcase, forcing the oil to cope with them.

So in short..Diesel oil recommendations are

Look for a Diesel oil specific (an oil primarily for Diesel Engine Use) A good quality 15W40 or 10W40 Diesel/Turbo Diesel Mineral or Semi Synthetic oil is the best choice.

We have purposely left out the arguments/reasons and discussions behind the more bizarre choices, settling on the 'knowns' here to help you make a more informed choice.

Previous information A viscosity (thickness) of 15w40 or 10w40, and an oil suited for Diesel engines. As noted earlier in this page, many modern oils are suitable for either petrol or diesel (read the label) but most 80/90 members feel that its best to find an oil that is primarily for diesel and preferably for Turbo diesel.

Quantities (as we note them):

1z TDI - 4.5 litres with the filter

Technical Specs Explained

(provided by member 'Oilman'

1) The purpose for which it is intended (i.e. engine oil, gear oil, ATF etc)

2) The viscosity (i.e. 10w-40, 5w-30 etc for engine oils and 80w-90, 75w-90 etc for gear oils)

3) The specifications that it meets (should contain API and/or ACEA ratings)

4) The OEM Approvals that it carries and the codes (i.e. MB229.5, VW504.00, . . 913A, BMW LL04 etc)

Ignore the marketing blurb on the label, as in many cases it's meaningless and we will explain later what statements you should treat with some skepticism. So, what does the above information mean and why is it important?

The Purpose

All oils are intended for an application and in general are not interchangeable. You would not for example put an Automatic Transmission Oil or a Gear Oil in your engine! It is important to know what the oils intended purpose is.


Most oils on the shelves today are “Multigrades”, which simply means that the oil falls into 2 viscosity grades (i.e. 10w-40 etc)

Multigrades were first developed some 50 years ago to avoid the old routine of using a thin oil in winter and a thicker oil in the summer. In a 10w-40 for example the 10w bit (W = winter, not weight or watt or anything else for that matter) simply means that the oil must have a certain maximum viscosity/flow at low temperature.

The lower the “W” number the better the oils cold temperature/cold start performance. I.E. 5w is better than 10w etc

The 40 in a 10w-40 simply means that the oil must fall within certain viscosity limits at 100 degC. This is a fixed limit and all oils that end in 40 must achieve these limits. Once again the lower the number the thinner the oil, a 30 oil is thinner than a 40 oil at 100 degC etc. Your handbook will specify whether a 30, 40 or 50 etc is required.


Specifications are important as these indicate the performance of an oil and whether it has met or passed the latest tests or whether the formulation is effectively obsolete or out of date. There are two specifications that you should look for on any oil bottle and these are API (American Petroleum Institute) and ACEA (Association des Constructeurs Europeens d’Automobiles) all good oils should contain both of these and an understanding of what they mean is important.

API Specifications

This is the more basic of the two specs as it is split (for passenger cars) into two catagories. S = Petrol and C = Diesel, most oils carry both petrol (S) and diesel (C) specifications. The following table shows how up to date the specifications the oil are:


SG - Introduced 1989 has much more active dispersant to combat black sludge. SH - Introduced 1993 has same engine tests as SG, but includes phosphorus limit 0.12%, together with control of foam, volatility and shear stability. SJ - Introduced 1996 has the same engine tests as SG/SH, but phosphorus limit 0.10% together with variation on volatility limits SL - Introduced 2001, all new engine tests reflective of modern engine designs meeting current emissions standards SM - Introduced November 2004, improved oxidation resistance, deposit protection and wear protection, also better low temperature performance over the life of the oil compared to previous categories.

Note: All specifications prior to SL are now obsolete and although suitable for some older vehicles are more than 10 years old and do not provide the same level of performance or protection as the more up to date SL and SM specifications, so if you’ve a recent model, don’t bother.


CD - Introduced 1955, international standard for turbo diesel engine oils for many years, uses single cylinder test engine only CE - Introduced 1984, improved control of oil consumption, oil thickening, piston deposits and wear, uses additional multi cylinder test engines CF4 - Introduced 1990, further improvements in control of oil consumption and piston deposits, uses low emission test engine CF - Introduced 1994, modernised version of CD, reverts to single cylinder low emission test engine. Intended for certain indirect injection engines CF2 - Introduced 1994, defines effective control of cylinder deposits and ring face scuffing, intended for 2 stroke diesel engines CG4 - Introduced 1994, development of CF4 giving improved control of piston deposits, wear, oxidation stability and soot entrainment. Uses low sulphur diesel fuel in engine tests CH4 - Introduced 1998, development of CG4, giving further improvements in control of soot related wear and piston deposits, uses more comprehensive engine test program to include low and high sulphur fuels CI4 Introduced 2002, developed to meet 2004 emission standards, may be used where EGR ( exhaust gas recirculation ) systems are fitted and with fuel containing up to 0.5 % sulphur. May be used where API CD, CE, CF4, CG4 and CH4 oils are specified.

Note: All specifications prior to CH4 are now obsolete and although suitable for some older vehicles are more than 10 years old and do not provide the same level of performance or protection as the more up to date CH4 & CI4 specifications. If you want a better more up to date oil specification then look for SL, SM, CH4, CI4

ACEA Specifications

This is the European equivalent of API (US) and is more specific in what the performance of the oil actually is. A = Petrol, B = Diesel and C = Catalyst compatible or low SAPS (Sulphated Ash,Phosphorus and Sulphur). These specs are more commonly found on European oils and in many respects are more important than API for European Manufactured cars. Unlike API the ACEA specs are split into performance/application catagories as follows:

A1 Fuel economy petrol A2 Standard performance level (now obsolete) A3 High performance and/or extended drain A4 Reserved for future use in certain direct injection engines A5 Combines A1 fuel economy with A3 performance B1 Fuel economy diesel B2 Standard performance level (now obsolete) B3 High performance and/or extended drain B4 For direct injection car diesel engines B5 Combines B1 fuel economy with B3/B4 performance C1-04 Petrol and Light duty Diesel engines, based on A5/B5-04 low SAPS, two way catalyst compatible. C2-04 Petrol and light duty Diesel engines, based on A5/B5-04 mid SAPS, two way catalyst compatible. C3-04 Petrol and light duty Diesel engines, based on A5/B5-04 mid SAPS, two way catalyst compatible, higher performance levels due to higher HTHS.

Note: SAPS = Sulphated Ash, Phosphorous and Sulphur.

Put simply, A3/B3, A5/B5 and C3 oils are the better quality, stay in grade performance oils.


Many oils mention various Car Manufacturers on the bottle, the most common in the UK being VW, MB, BMW, . . or Vauxhall but do not be misled into thinking that you are buying top quality oil because of this. Oil Companies send their oils to OEM’s for approval however some older specs are easily achieved and can be done so with the cheapest of mineral oils. Newer specifications are always more up to date and better quality/performance than the older ones.

Some of the older OEM specifications are listed here and depending on the performance level of your car are best ignored if you are looking for a quality high performance oil:

VW – 500.00, 501.00 and 505.00

Later specs like 503.00, 503.01, 506.00 are better performing more up to date oils but as far as VW is concerned even these have now been superseded by the latest VW504.00 and VW507.00 specifications.MB – 229.1, 229.30 Later specs like 229.31, 229.5, and 229.51 are better performing and more up to date oils. BMW – LL98 Later specs like LL01 and the latest LL04 oils are better performing and more up to date.

Finally Above is the most accurate guidance we can give without going into too much depth however there is one final piece of advice regarding labelling. Certain statements are made on labels that are meaningless and just marketing hype; here are a few to avoid!

- Recommended for use where……………

- May be used where the following specifications apply……………

- Approved by………………………..(but with no qualification or specification)

- Recommended/Approved by (some famous person, these endorsements are paid for)

- Racing/Track formula (but with no supporting evidence)

Also be wary of statements like “synthetic blend” if you are looking for a fully synthetic oil as this will merely be a semi-synthetic.

Like everything in life, you get what you pay for. The cheaper the oil the cheaper the ingredients,lower the performance levels and older the specs it meets so beware!

Good links

Oil Changes - Petrol Engine

Oil filters and recommendations


But in some cases its much easier to post this pic: