Theoretically, IMHO, with a stock-ish GP running 10W-30would/should idle a bit quieter. Mylogic is thinner oil favors the valve train/upper end and thicker oil favors thelower end bearings. And considering thehydraulic valve lifters are pretty much like honey badgers (they don’t give af&^%Originally Posted by GTP in RTP
the difference would be very slight. Unlike mechanical lifters that can be very particular on oilchoice. Now if you have lower end issueslike piston slap the 10w-40 might be quieter over all. But really 3800s are so solid anyone that hasbeen around them knows the flavor and viscosity (within reason) of the oildoesn’t matter.
Just to tack this on, with all the above said, many ppllike to run 10W-40 because it does give a little more protection in the lowerend were 3800s tend to fail when overly stressed.
