Why would you NOT use 0W-xx?

[MonumentOiler]

The problem of not starting in the middle of nowhere at -22 deg f. is a much bigger deal than reducing the OCI because the oil could have some greater susceptibility to shear.

UOA of the two different oils in the same engine over identical operating conditions would tell the story. Probably pretty hard to arrange unless you had a twin engined airplane.

 

[mongo161]

There is still not widespread availability of 0W by oil producers. Maybe in the future this will hold true but for now I stick with 5w30 and on occasion 05W-40 in Shell Rotella. I've never seen a need to run 0W oils.

When I do run the Shell Rotella T6 it is 1 Gallon mixed with 2 Quarts of Formula Shell 5w30 conventional. It works for me in that combination with the oversize Oil filter.

 

[JohnnyO]

I use Mobil 1 0w30 in my 4.0 Sport Trac. The used oil analysis are fine.