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PLEASE NOTE THAT THIS FAQ IS OUT OF DATE. Work is being done to move this to a wiki format with updated information, but please check out the TDIClub forums (http://forums.tdiclub.com) in the mean time for more updated information.

TDI FAQ




4) Oil
    1. Specifications - The oil specified for use in the Volkswagen TDi for current models meets the "API Service CG-4" rating. This mark means that the oil has been tested for use in Diesel (C = compression ignition) engines to meet the requirements of a test level called "G" in a 4-stroke engine. The oil may also have been tested for use engines fueled by gasoline, methanol, propane, or other fuels ignited by a spark plug (S = spark ignition). The "S" ratings (SG, SH, SJ, etc.) have no bearing on the suitability of the oil to protect a Diesel fueled engine from the special demands imposed by the higher compression ratios and the tendency for all diesel engines to place soot in the oil.

      Since there is little difference internally between the earlier and later engines, it is only prudent to use oil meeting the latest standards, even in the earlier models. The latest standard is CH-4, and the one previous to that is CG-4. Many oils which have CG-4 printed on the packaging actually meet CH-4, but due to the time taken to use up old packaging, it is only the labeling which is not up to date.
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    2. Semi and full Synthetic - According to a service bulletin, Volkswagen recommends the use of synthetic oil in the TDI engine. Herein lies the dilemma, as if you take your Volkswagen to a dealer for service, they may try to use an oil which is not CG-4 rated and isn't really a full synthetic. There are a limited number of oils on the market in North America which satisfy the following criteria: CG-4 or CH-4 rating, full synthetic, viscosity 5w30 or 5w40. These oils are suitable for VW's full recommended oil change interval and the viscosity range is suitable for all climates in North America. Contrary to what dealers may tell you, neither Mobil 1 nor Castrol Syntec fulfill all of these requirements - and that information is right on the bottle.

      The information in this section refers to API service classes which are North American standards.  Different standards for engine oils are used in Europe and elsewhere. It should be noted that since this vehicle was developed in Europe, it is much easier to determine whether a European engine oil is suitable. Any synthetic oil meeting the specification VW 505.00 is suitable for use with this engine with the full recommended oil change interval.  The VW 505.00 is the manufacturer's own specification, but in North America this specification is rarely seen, so we must rely on the API grades.

      Oils which are suitable for the full recommended oil change interval in all climates include, but aren't limited to:
      Mobil Delvac 1, 5w40 (full synthetic, a reformulated version of Mobil 1 which is intended for diesel engines)
      Chevron Delo 400, 5w40 (full synthetic version)
      Shell Rotella T (full synthetic version, not to be confused with Rotella SB synthetic blend or regular Rotella T non-synthetic)
      Amsoil Series 3000, 5w30 (full synthetic, CH-4 rated)
      Amsoil High Performance, 10w40 (full synthetic, CH-4 rated)
      Amsoil semi-synthetic 15w40 (CH-4 rated and high quality, but almost as expensive as the full synthetic, and higher viscosity at low temperatures)
      Redline, synthetic version (make sure you get the type meant for diesel engines, with the CG-4 or CH-4 rating)

      There are intermediate classes of oils in between full synthetic oils and conventional oils.  These include synthetic blends, and so-called "Group III" hydroisomerized oils, and are also available in viscosity ranges suitable for all climates. They include:
      Shell Rotella SB (synthetic blend)
      Petro-Canada Duron, various viscosity's (Group III, various grades available, ensure CG-4 or CH-4 rating on the bottle)
      Castrol Syntec 5w30, 5w40 (Group III - note that this oil is frequently recommended by VW dealers but is NOT rated CG-4 or CH-4, and isn't a full synthetic - which calls into question what the dealer is telling people ... this forum is generally of the opinion that Castrol Syntec is not the best choice for this engine)

      In warm weather, a good-quality non-synthetic oil meant for diesel engines with CG-4 or CH-4 ratings may be used. They're not suitable in cold weather due to reduced cold-pumping properties, and it's prudent to shorten the oil change interval because non-synthetic oils may not resist breakdown at high temperatures as well as the synthetic oils (remember that turbocharger). These oils are much easier to find. These include:
      Mobil Delvac 1300, 15w40
      Shell Rotella T, 15w40
      Chevron Delo 400, 15w40

      Beware of other brands that claim to be diesel-rated or turbo-rated, but are actually just plain cheap. Use the good stuff. If you doubt this, ask transport truck drivers that own their rigs what they use. Chances are it will be Delvac or Rotella.

      In cold weather, if CG-4 or CH-4 rated synthetic oil cannot be found, regular Mobil 1 rated CF in viscosity grades 0w30, 5w30, or 10w30 may be used, but with a shortened oil change interval because this oil doesn't have as much capability to handle soot.

      So what's the deal if something else is used besides the expensive and sometimes hard-to-find 5w40 full-synthetic CH-4 rated oil?

      Conventional oils that are meant for diesels are usually viscosity SAE 15w40. That's okay in warm weather, but not in cold weather. You want oil to reach that turbocharger as soon as possible after a cold start, and it takes longer to get there if the oil won't pump easily. Synthetic oils have many advantages over conventional oils, not the least of which is better cold pumping characteristics, and hence the common 5w40 viscosity grades.

      It is possible to get some non-synthetic oils with viscosity's such as 0w30, 5w50, etc. In non-synthetic oils, these can only be achieved by heavy use of viscosity-index modifiers, a type of additive, whereas synthetic oils can easily achieve a viscosity range like 5w40 with little or no use of viscosity-index modifiers. For various reasons we'd rather not get into, it's better to have the viscosity right in the base stock, than to tinker with the viscosity using additives.

      Oils that lack the CG-4 or CH-4 rating don't have the same level of anti-foaming and soot-dispersing capability. The best quality diesel-engine oils deal with it and render the soot as harmless to the engine as possible. Oils that don't meet the CG-4 or CH-4 ratings can't handle as much soot, so you need to change them sooner.

      Finally, cheaply made oils (not the same as cheaply priced ...) usually won't have the same resistance to breakdown at high temperatures, that good quality oil does. High temperatures are found in the turbocharger. When oil breaks down at high temperature over a period of time, it "cokes" or builds up deposits in the high-temperature area, which then restrict lubrication. Bye-bye, turbo. There has been one reported turbo failure which was traced to lubrication failure. Do a search of the forums for "turbo failure" to find out what oil he was using...
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    3. Additives - Volkswagen specifically recommends not to use oil additives. The use of additives may adversely affect your warranty. After the warranty period expires there is nothing to prevent the use of your choice of additives, although members of this forum "in the know" indicate that there is generally more to be lost than gained.

      Many oil additives contain PTFE, also known as Teflon, and touted under many other different names after the manufacturer of Teflon filed a lawsuit to prevent oil-additive companies from using that name. PTFE is a solid. The job of the oil filter in your engine is to collect solid particles down to about 10 microns in size. Where's that solid PTFE going to end up? In the oil filter. Which may cause the filter to plug prematurely, causing the bypass valve to open, and now your engine is running on unfiltered oil. Not good.

      Other oil additives are nothing but ultra-thick substances that increase the viscosity of the oil in an attempt to reduce the leakage rate around seals that have seen better days ... better off to just change the seal. This may help reduce oil consumption on a knackered engine which is on its last legs and is not worth rebuilding, but it can do no good for an engine which isn't leaking or burning oil.

      There are some oil additives which contain real anti-wear additives, such as ZDDP (zinc di-horrible-chemical-name phosphate). ZDDP is a useful additive when used in the right concentration, and in combination with other additives. Good diesel motor oils already contain the right amount of ZDDP and other additives, more is not necessarily better. Why risk it with home-brewed additive concoctions when you can just buy the right oil that has been engineered with a balanced additive package?
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    4. Oil consumption - Engine oil consumption rates will depend on the viscosity or weight of the oil, engine speeds, weather, road conditions and other factors. Volkswagen has mentioned these variables in declining to state a "normal" consumption rate. Higher speeds and a new engine will tend to consume more oil than lower speeds and an engine which has been broken-in.
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    5. Where to get - For the picky owner interested in only the best, it can be difficult to find oil that meets the recommended criteria. In the USA, Mobil has a find-a-dealer page at www.mobil.com and in Canada, Mobil is distributed at Husky truck stops, among others.

      The most common diesel-engine vehicles on the road (in North America) are ... big trucks. Those big rigs have big diesel engines, so if you want to find products and lubricants for diesel engines, go where the big rigs go. Truck stops, and bulk lubricant-supply places.
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    6. I just changed the oil, and it's still black. Why? - Diesel motor oil usually turns black in absolutely no time, because diesel engines pump soot into the oil.  It's totally normal and it's a fact of life with a diesel engine. As long as the oil in the crankcase is the right stuff (rated CG-4 or CH-4 and good quality, not cheap stuff) it will handle it. Don't worry about it.
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    7. Can I get the oil changed at a quick-lube place? - Yes, but ... Make sure you know what's going into your engine. A recommended procedure is to BUY YOUR OIL SOMEWHERE ELSE, so that you can read the label on the container and know exactly what it is. See the section above for recommended oil types. Bring YOUR OWN JUG of fresh oil to the oil change place and watch the mechanic pour it into your engine. Also be aware that many (most?) quick-lube places do the job in a hurry and thus overfill the oil. The oil capacity of the crankcase is such that one 4-litre jug will put the oil level pretty close, without overfilling it.
    8. Synthetic oil is too expensive. Can I mix it with regular oil? - In an emergency on the road when you need a litre of oil added to get home, by all means do it. As a routine matter, oil experts advise against mixing types and brands. Each type of oil has a certain additive package which is meant to work a certain way, and it will be less effective if diluted with something else. Besides, by using that expensive full synthetic, oil change intervals can be longer, so it's really no more expensive - and it's less hassle - in the long run.

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      All information Copyright 1996-2002 Fred Voglmaier.
      All rights reserved. This FAQ (Frequently Asked Questions) may not be reproduced without written permission.

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