Change SAE 30 for winter or not?

[Chris142]

Originally Posted By: Drew99GT
Chris, don't you have some Chevron 10w-40? I'd use that; it has 200 ppm more phosphorous then regular SM/GF-4 oils.
I've got cases of it!

I'd also like to run the Rotella 10w30 but I have not found any.

 

[addyguy]

Personally, I'd just keep running the 30. Modern 'straight 30's', made from group II/II+ base oils, have such good specs that they are, in reality, closer to a 15W-30. You can use them in pretty much any temp range you would use 15W-40 in.

A big, tough old engine like that isn't going to hurt on SAE 30, even down to 25-30 degrees F.

 

[Drew99GT]

https://cglapps.chevron.com/msdspds/PDSP...&lbCompany=

Look at one of the Chevron Supreme English SM data sheets. It shows that the 10w-40 and 20w-50 have more zinc and phosphorous then the fuel economy grades. 10w-40 would be perfect for your old truck. Might be good year round!