Just to offer what I know, and certainly not to try to answer a question in lieu of, or for Larry Bible.
Lubrication in general has become much more advanced than it was even 10 years ago. The "new" synthetics, like Mobil 1, are well beyond where they ever were. Mobil 1 actually has a new formulation that is based upon three synthetic base polymers, hence the "Tri-Synthetic" name. I recommend you check out: http://www.mobil.com
for more information. You could also go to: http://www.castrol.com, http://www.valvoline.com
, and http://www.redline.com
just for starters. I, for one, have learned a lot. Both from going to their websites, and
from participating in this forum.
As for tolerances, even the term itself is no longer appropriate. Tolerance indicates allowable deviation, or margins for error, and with the exact and precise computerized milling machines that Mercedes now uses, there is no need for tolerance. When you add to that, the continued advances in metallurgy (also thanks to computers), then you will find that the alloys and other metals being used in manufacturing the engines really are
quite different than ever before.
When you also consider the other advances in not only automotive ignitions, fuel metering and delivery systems, cooling systems, and emissions controls, but also in the computerization of those systems, you will find that it adds to the overall "cleanliness" of the interior of those motors to such a degree, that the first oil change is recommended by Mercedes at an unheard of before now, 10,000 miles!
All of the "new" advanced lubricants, and coolants will also safely allow for a dramatic increase in their own change intervals, even in older vehicles made before that technology became available.
Unless, of course, you choose to "change it hot, and change it (more) often"...
[Edited by longston on 01-31-2001 at 10:37 PM]