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

Oil comes to the user in various viscosity ranges and meeting certain specs or test standards. Generally, European cars require an oil that remains thicker at operating temps than other makes. Basically, these cars need a 40 weight oil verses the common 5w-30 conventional oil used in most vehicles.
The common viscosity grade of 30 weight is what Quick Lubes will install in your car if you do not specify a thicker 40 weight oil. If thinner oil is installed, likely result is increased consumption and excessive wear. It is not the end of the world for one short interval if it's not mid-summer and you keep it topped-off. Keeping the oil level Full is the single most important thing the owner should be aware of. If you are not sure of the rate your car burns oil, reset the trip-o-meter and check the level after 1000 miles to ascertain a baseline.

"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.
We'll leave the subject of synthetic oil behind for now, but as it pertains to viscosity and "W"ratings, a synthetic formulation allows a wider operating range. For instance a 5w-40...a thick 40 weight at operating temp that can crank and flow in the cold, meeting the 5w test protocol. 0w oils are necessarily synthetic too, passing a cold cranking test at -35f!

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
229.3 or 229.5, BMW LL, Porsche Approval, or GM LL-205 are all high quality oils. There is also a generic ACEA "A3" spec that most Euro specs are based on. In short, Castrol is the Official oil of Audi and they offer a 5w-40 that covers most of these specs, also there is a 0w-30 (a thick 30) imported by AutoZone from Germany. German Syntec or "GC" is Factory-Fill in newer Audis and carries specs from all manufacturers It is unique in many ways and can be considered the best over-the-counter product for our cars. Heavily modified cars might consider a heavier oil, like a 5w-50.

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.
There are what is known as "strait" weight oils, but they are rare...a strait 40, for instance. Usually they are outdated, for older applications and should be disregarded.
So, we have left- 0w-40, 5w-40, 10w-40 and 15w-40. Obviously, the most extreme cold conditions require a synthetic formulation, the 0w-40 or 5w-40.
How cold then, can the 10w-40 and 15w-40 be used? I have a silly rule that I made up for that, but I think it is 100% accurate and easy to remember. Say a 15w might be good down to +15f and a 10w-40 is good down to +10f. If you see single digits more than once or twice a winter season, you probably want a 5w and if it gets below zero farenheit. A 0w oil might be the way to go. These are relatively conservative recommendations, exceeding the lower temps a few times a season is ok.

SERVICE INTERVALS

Now that selecting an oil viscosity is second-nature, let's look at service intervals.
Conventional oils, like 10w-40 and 15w-40 (diesel-rated) are vastly improved over their previous formulations of just a few years ago. They are the equals of synthetic oils of not long ago as far as service life goes. That is to say, the old notion of 3000 mile changes is just that, an old notion.
Now we see a $2 oil that offers a service recommendation from it's maker, "5000 miles" or 7500 for a semi or Synthetic Blend. That is very realistic.
There is one way to know how your oil has held up in your application...send a sample to the lab for a UOA, Used Oil Analysis. The report will show how much metal has worn away from the engine internals and where in the engine it came from. Lead comes from bearings, chrome, tin and copper comes from rings, aluminum or iron form the block. The lab can also determine how much useful additives and "life" is left in the oil as well as the presence of glycol....a dreaded coolant leak. It's fun stuff, but a bit advanced for this article. As a general rule, say a good conventional oil can go 6000-8000 miles unless you do mostly short (<10 mile) trips where the oil does not get fully heated to operating temps to burn away condensed water and fuel. Old oil and water mixed and warmed...yuk, sludge. If you do short trips, maybe 5000 miles on a semi-synth oil is a good practice.

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.
Generally, they are formulated a bit thick for their stated grade and offer excellent service life. Audis typically have weak seals and Hi-Mi oils are a very good solution. One blender even offers a synthetic Hi-Mi oil that should be considered one of the best synth oils on the market. Their Hi-Mi synth is a rare thick 30 that carries Euro specs.

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
difference) The main point is to immediately drain it out afterwards with the dissolved sludge, before the solvent evaporates and re-deposits the sludge. Another product exists that is based not on harsh solvents but on esters used in industry for metal cleaning. It is slow-acting and gentle with the added benefit of reconditioning seals. Mechanical devices that pump hot solvent backwards through the engine's oiling system exist and are well-regarded in their degree of effectiveness. Any of these processes, and especially in combination, should be consider safe and effective in the opinion of the author.

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!