Good points, Plugot, but if you do a cost-base analysis the extra time given by the synthetics does not offset the costs. And the high-bore 8 cylinder of the Corvette is way different than the Mini's cooled-as-it's-sprayed on oil cylinder. And the whole "oil breaks down and loses viscosity" thing is way over rated when it comes to the longevity of engines.

About 15 years ago a guy did a study - I can't remember his name, but it was someone like Jack Smith who had a nationally syndicated newspaper column, and he went after the whole "we must change every 3000 miles" oil thing. He thrashed his Ford, a truck I think, *never* changed the oil, only changed the filter and just made sure it always had enough oil, then took apart the engine, measured the cylinders and seals for leaks and wear and tear. Everything was fine.

Of course, cars were simpler back then, but they were also much more poorly made back then too.