Originally Posted By: Thetruck454
To revisit this, I ended up going with M1 0w-40. About the only difference I've noticed is mpg has dropped a good 3 mpg when cold (short 30 min trips) and about 1-2mpg on a good long trip where the oil temp is at 220. Since winter is coming, I'm wondering if I should switch out to a thinner oil as I can't get out of my heard that less mpg = more wear though I keep reminding myself it's due to the thicker weight only. I was looking at M1 AFE 0w-30, Amsoil SSO 0w-30 and Redline 0w-30.
I've heard RL is the absolute best, but not very good at OCI's longer than 5,000 miles. So far following the OLM my changes have been around 7k miles, so if I want to go the RL route, I'll need to ignore my OLM (Annoying, but not a deal breaker). Also I've heard M1 AFE 0w-30 doesn't have nearly as good of an additive package as the 0w-40(though I don't quite understand this), so that doesn't make sense. That leaves me with Amsoil SS0 which looks to do pretty good with a Vis @40 of 58.2, Vis @ 100 of 10.5, a VI of 171, and HTTS of 3. How does the additive package stack up and should I have any fear of this oil not holding up to 700hp as needed? I don't intend on using the huge 10k+ miles OCI's but would changing this oil at 7k miles be a huge waste?
The 0w40 has more zinc and other additives vs theM1 AFE. Has to do with API SN allowing more zinc for 40 and up.
For your application I'd stay with the 0w40 for a margin of safety when you get on the throttle.
If you go down to a 30 stick with something on the thicker end.
For the power density of that engine you need to stay on the thicker side of life if you plan to use the power. If not and you want mpg the 0w30 is a great choice. The M1 5w-30 is slightly thicker, with M1 HM 10w-30 coming in just under the 0w40