European cars require more specialized oil service than other cars. Owners of premium marques, like Audi, should know what to do and what not to do in order to keep their engines correctly serviced. The intent of this article is to offer a frame of reference for owners, either do-it-yourselfers or people who want paid service- they should know what to ask for. The progression of topics, ideally, will be from the basics to slightly complex and from maintenance of newer vehicles to reviving a used car that may have a dubious service history.
OIL SPECS AND VISCOSITY GRADES
"W"ratings- Motor oil essentially can be formulated within a range of thickness or thinness. That is to say, biased either thicker or thinner. Oil is known as a "Non-Newtonian fluid" whose viscosity changes as it's temp changes, unlike water that stays the same viscosity. A thin oil, like 5w-30, will flow great in cold when the engine is first started. In effect, it will not get too thick when cold but as the engine heats up, it will thin down as it reaches operating temp, ideally +212f (the temp it's SAE viscosity is measured). A thicker oil, like a 10w-40, will be significantly thicker in cold, to the point of inhibiting the engine from cranking and being lubed adequately as it warms up. That's how we arrive at the most common conventional grades of motor oil, 5w-30 and 10w-40. The "W" part just means that it passed a "cold cranking" test at very low temps.
Now, let's say we have a Euro car that requires a thick 40 weight oil at operating temp, but we want to start it in frigid temperatures, say -10f or -20f. How can we have an oil that will remain thin enough in the cold to allow cranking and flow, but stay thick enough to keep engine parts separated at operating temps? That type of service requires a synthetic oil formulation. Synthetic oil is also ideal for turbo applications too. As the oil is pumped past the turbo to lube it and carry away heat, a small fraction of it is potentially flashed off and leaves a residue behind in the form of coke or sludge. Synthetic oil leaves a minimum of these deposits.
The w-ratings and SAE viscosities we have referred to are part of API or American Petroleum Institute norms. They appear on oil bottles to denote the viscosities. Other specs are part of the labeling and test sequences pertain mostly to their service life and physical characteristics, such as the API "service grade" (SM) for American applications and ISLAC (GF-4)for Asians and ACEA (A3) for Euro specs. There are also manufacturer specs. Relevant mfg specs for Audis include: VW 502 (basic service, aka the "Turbo" spec), VW 503.01 (Long-Life spec for extended service intervals) VW 505/505.01 are for diesel applications. There are also newer VW specs coming from Europe that consolidate gas into VW 504 and diesel into VW 507. If you see any Euro specs on an oil, likely it is very good and can be used in a VW. Mercedes
Non-turbo Audi engines do not need specialized oil. Any 40 weight oil will provide low wear and acceptable consumption. Look at the "W"-rating and compare to the coolness of the climate you want to start your engine in.
As for synthetic oil change intervals...European specs are based on 30,000km (18k mi) intervals. However, in Europe, they pay $20-$25 a liter for the same synth oil we get here for $5-$6/qt. So, the incentive to change more often than 18k miles is there. Sludge problems with the 1.8t in longitudinal applications (A4, Passat) make 5000 mile changes with synthetic oil quite reasonable. For quick DIY changes, there is a tool known as an oil extractor pump. It pulls warm oil out through the dipstick tube, getting 90% or more oil in a matter of minute, without even putting a knee on the ground! You can pump out your old oil and refill it (preferably with the same kind) for the cost of a few quarts. No wrestling with the belly pan and you can leave the filter on for another interval. (A common practice in Europe and with other makes of cars) One brand of extractor that works well (although I am trying to stay away from specific brands) is Pela. In non-turbo cars, good synthetic oil can go over 10,000 miles, easily. Another way to plan a service in not by exact miles, but by time intervals. Changing 2-3-4 times a year based on the miles anticipated and driving conditions works for several reasons. Changing viscosity for seasons or planning service visits on days off from work are good reasons for time intervals. Not counting down miles also helps maintain a degree of sanity.
Another oil product that should be mentioned here is Hi-Miles oil. Hi-Mi oil is generally formulated like a semi-synth oil but with additves that helps make seals clean and soft after they have become dirty and dried/brittle.
One final point of specialization is how to clean an engine in a used car or an engine that you might have gone too long between changes with or not used synth oil when it should have been. Generally, more frequent changes is a good start. Longer intervals assumes you are starting with a clean engine to begin with. The 15w-40 diesel-rated oils contain the most cleaning additives, if your outside temps allow it, it's a decent way to begin some light cleaning. Other methods include the old-timer technique of adding a quart of Kerosene into the old oil of an idling engine 10 minutes before draining and changing it. (Some people use SeaFoam or Berryman's B-12...same
Go ahead, pick an oil visc that is appropriate for climate, for desired service interval or turbo application and as far as brands go, they are all good....even go for the one Grandpa used or the colour of the bottle!