- Jun 30, 2022
- Reaction score
- Ram Year
- 5.7 Hemi
So would it be better to run 0w40 in an older hemi?Since you brought up amsoil, look at their sheets. 5w30 operates at 10.3 visc, 5w20 operates at 8.8 visc, now look at the next weight up which is 0w40 that operates at viscosity 14.8. The point is 5w20 and 5w30 are thin oils not much difference either way, the 5w30 will give you a little more film strength. You can see when you jump to 40 weight you have a real heavy duty oil, whereas 5w30/5w20 are just your basic passenger vehicle oil. For a 2012 no doubt you want to be thicker, as tolerances widen you don't want thin oil. If you get a used oil analysis sometime, post it in blackstone thread in 4 gen performance section for feedback on what your engine is doing.
EPA uses CAFE standards to force manu's to use thin oils. Since CAFE is impossible to make the goals of, manu's need to prove they tried everything. It has been posted ad naseum. FCA engineers made hemi specific oil 0w40 for a reason, but they literally cant use that oil in a 1500 non HD vejicle.