Oil Level - How Important Keeping It at Top Mark?

[SchlockRod]

The TBN (total base number) is always part of an oil analysis. If it gets too low your oil is too acidic. The acids form mainly from water (water vapor being one of the main by-products of combustion) condensing in the oil and forming things like H2SO4, etc. You'll get way more of this kind of thing if you do a lot of short trips, especially in cold &/or damp weather. The engine oil doesn't get hot enough to evaporate out the water. But over time you'll get acids under any operating conditions.

The type of driving you do, and the climate, has a great influence on your oil's health. These are significant "variables" as Doc mentioned, and you can't rely on a study of someone else's conditions to determine your oil's health. You can get an oil analysis done. Snider petroleum will send you a kit and instructions, and for about $20 you will get an analysis report on your sample. This is typically something only fleets do; it may not make economic sense for you (risk/cost/benefit analysis). Anyway, the industry consensus seems to be that 3000 miles is probably too often for most drivers, and that 5000 or 6000 makes more economic sense with today's engines & oils. But maybe the best thing would be to just follow your owner's manual. The OEMs know pretty well what their engines need. One other thing: If you live in Michigan, you may not want to change oil at all; the engine should outlast the car as salt, huge gaping potholes, and untrained, drunk, or otherwise unqualified drivers do their damage.

SNIDER PETROLEUM
P.O. BOX 368
13401 Valley Avenue E.
Sumner, WA 98390

Phone: 1.800.77.FUELS - 1.253.863.6341

[email protected]
http://www.sniderpetroleum.com

BACK TO THE TOPIC OF THIS POST:
The technicians who write for the Mercedes-Benz club magazine The Star state that you should only add oil when it gets to the "add" mark. They said that often an engine will actually find a level at which its oil level stabilizes. That level may be slightly above the "add" mark. Above that, it will disappear quickly and adding oil may actually be wasteful.
Also, be sure to follow the owner's manual on the procedure for checking oil level (correct temperature is key, letting the car sit for five minutes after shutdown or whatever, and also being on level ground, etc.)

[Mike_Van]

For a normally aspirated engine like my '96 3-cyl., I am unconcerned about the maker of the oil, provided it has the correct industry spec, but I like to go with companies that do the least business in the Middle East.

For my turbo diesel VW, I only use synthetic, as it provides lubrication for the turbo, and conventional oil can coke it up.