Originally Posted By: Noey
So many opinions, so much of it totally wrong. Which is OK b/c it's not their car, right?
I'll give the right answer here and try to be as concise as possible so it doesn't confuse. And please, I'm not auditioning for your approval, this is the right answer.
You should use what Ford recommends.
There's no correlation btwn the weight of the oil and engine longevity. If anything, you actually improve the chances of changing the longevity...for the worse...if you monkey around too much with viscosity. That's b/c the thickness of the oil specified by the engineers...you know, those actual folks with advanced degrees who designed your engine, not a bunch of self proclaimed know it all's on a website..take things like load, heat dissipation, bearing clearances, etc. into account.
You obviously have no idea how the corporate structure works in the automobile industry! The "Engineers" that know it all are heavily influenced by the bean counters and the EPA/CAFE. The US has the lightest oil weight specs of any country by a long shot. Just research the manual and oil suggestions for your same car in other countries. Almost NO ONE uses 0W20 anywhere else in the world, why? because they would rather trade that .0001% fuel economy for longevity! In the USA its totally backwards.