Originally Posted By: HKPolice
Is the engine spec'd for 5w30 or 40? If you run 40 in a 30 engine it'll run hotter.
Really.
Got any evidence of this.
I run 40 grades in my rt charger in the summer and 20 grades in the winter and I can tell you with 100% certainly that oil temps are actually lower with the thicker oil by 10-15f.
So if you've got any evidence I'd love to see it.
OP
Unless you operate the vehicle under extreme conditions and elevate oil temps significantly there's no point in running a thicker oil than specified.
For example my mustangs and charger. In the summer I run a euro spec 40 grade because I beat on the vehicles driving them significantly harder and regularily elevating oil temps beyond 275f and I've seen oil temps in excess of 300f,which in my opinion it too hot for a 20 grade to maintain film strength.
I might be wrong however I'd rather not find out the hard way I'm right.
In the winter I use a quality 5w-20 because rarely are oil temps elevated beyond 230f.
My charger,in the summer,using a 5w-20 will stabilize oil temps of 213f. Using a 0w-40 in the same conditions,oil temps stabilize at 185-200f depending if I set cruise at 55 or 75.
If anything is go a bit thinner instead of thicker. Oil pumps faster to the critical moving parts.
If the engine is noisy add a can of liqui-moly mos2 and the noise will vanish within 300 miles.