Exactly, until the filter clogs (which on most cars wouldn't happen until at least 15,000 to 20,000 miles), the filter continues to improve in efficiency. Fact of life.

Where are you getting this stuff? The fact is that at operational temperatures, 0W-20, 5W-20, 10W-20, 15W-20, and even 20W-20 have a virtualy identical viscosity, so no, 10W-20 will not be able to allow an engine to achieve any improvement in fuel economy, in fact, quite the opposite. The thing is, the thinner the oil is following a cold start, the faster it pumps up to the top end of the engine, and the better the fuel economy while the engine is warming up; once warm, all things are pretty much equal.

As for what the ASE recommends; please provide a link to the fully qualified recommendation. Said another way, I don't believe the ASE would be so stupid to make such an irresponsible recommendation.

 

Well I'm currently in school at wyotech and this is just what my instructors have taught us. Obviously oil is a never ending debate. No one is ever happy. I'm just going to keep listening to the guys who are certified master mechanics from ASE.

 

How about us Engineers? Certified Master Mechanics are just that, mechanics.