There are multiple reasons for a 0W-20 or 5W-20. It's not just fuel efficiency.

They both meet all SAE 20, and SAE 5W requirements. The 0W-20 also meets SAE 0W.

Remember the old 20W-20 multigrade oil that was common in the 1970s & early 1980s?

The XW and... Login to read more.