[RaceAddict]

Originally Posted by removedonut

0W20, 5W20, and 5W30 are all accepted oil weights (to run full-time, not just in a pinch) in the australian and japanese owner’s manuals. They have the same engines. The TMNA insistence on 0W20 is almost assuredly just for fuel economy reasons.

100% agree with that!

Like anything else you may read/watch on the internets, feel free to take anything I'm saying with a grain of salt, do your own research etc... but it seems to me that 0W20 being recommended as a one-size-fits-all solution is entirely down to EPA mandates and automakers striving to hit fuel economy numbers.

Here's an article from 2012, which I believe is a year after the 0W20 mandate came into play:
https://www.consumerreports.org/cro/...cars/index.htm

I'd suggest it has nothing to do with "tighter manufacturing tolerances" and everything to do with legislation.

And remember, the EPA doesn't care how long your engine lasts.