OEMs Press for Light-vis Grades

 

Interesting.... -15w 20

 

As long as the engine is specd for it and the tolerances need something thinner, all will be good. Just like how well 5w-20 does in engines now. Even in a 300+ 4.6 liter ohc, it brings back excellent uoa's. Im on a phone browser so I didn't open the link yet, but I wonder what engines will be using this thinner oil?

 

At operating temp, Not all engines oil pump can provide the flow/volume needed with lower viscosity lubes & the manufacturers aren't likely to spend the money retest older engines for wear in the pump & or engine, to determine if the pump can keep up.

As an example, Fords 4.0L comes to mind, as it was never back speced to use 5W-20.

Using a lower viscosity crankcase lube than specified, isn't likely to make a measureable mpg difference to the average driver anyway.

I never changed my 3.8L over to the back speced 5W-20, as it's doing just fine on 5W-30!!!!

 

I wouldn't either. The 05 Mustang GT calls for it, though. My mom isn't a hot rodder, plus all the 4.6 ford UOA'S I've seen made me want use Pennzoil Platinum 5W-20 in her car. I do hot rod it, though, lol, and the factory gauge always sits high. But those modular engines do great on thinner oils no matter what.