LOL. Been running 20w-50 Valvoline racing since the 70s. Not molasses or even close. I even run it in a 96 Neon and 2001 Cherokee, that both still run like new. Where do people get these wrong ideas?
Yep. Anyone who's pulled a drain plug on a hot engine full of 20W-50 isn't thinking about molasses.
The difference in viscosity between a grade 30 and grade 50 at 100°C is small, yet there is a difference in oil film thickness.
