BUT, that same engineer is also working for a company that stays in business by selling cars. In the 1950s, Porsche started a project on a 10 year "minimum maintenance" car, but dropped it when told what it would do to the company financials if they succeeded. I would bet the service recommendation that the designer/engineer would recommend privately may be different from the one the company marketing people published in the owners manual!
For most owners with a 3-5 year ownership (lease?) period before they "need" the latest and greatest car to carry around kids or clients, the owners manual probably is a reasonable guide. For the fanatic who wants to own the car forever and keep the car on the road as long as possible, I submit that the owner's manual should be considered a MINIMUM service guide. But then, I'm the Obsessive/Compulsive type who has replaced timing chains/belts 10k miles before the recommended interval. (Why? Because a friend of mine once had the timing belt on their BMW fail several thousand miles BEFORE the "designer/engineer/builder" specified change interval, to which BMW USA said "out of warranty, too bad about your valve train, will that be cash, check, or credit card?"!!!)
I know I'm paranoid, but am I paranoid enough!
[Edited by JCE on 01-06-2001 at 02:23 AM]