Originally Posted By: Garak
Originally Posted By: kschachn
OK good explanation, thanks. I guess I was mixing up 5W-XX with 0W-XX too.
Yep, that's the big thing to watch. The 0w-20 is usually better in the absolute cold than the equivalent 0w-30, but of course the 5w-XX will not be as good as any 0w-XX in the cold. That being said, I've used a lot of 5w-XX grades in the winter, and we have bad ones. To me, the difference between GC 0w30 and Mobil 1 0w-40 in the winter would be splitting hairs. Either would be significantly better in the extreme cold than another notable example with an HTHS of 3.5 or higher, a 10w30 HDEO.
THAT'S what I was trying to question in the post above, as I was referencing Mobil 1 0W-40 in comparison to GC, NOT any 5w-xx oil.
Does the Mobil 1 product not have a much better VI than GC, as well as at least a comparable if not superior MRV??