FE Engine Oil

[RET_COP]

Gibbs is a good product as well as others, you can do a search.
The LIGHTEST oil that works in your engine. Like Dan said clearances are a big factor.
I would like to know why KC recommends 50w oil.
If your engine has good pressure with a lighter oil I would start there.
I have heard hydraulic lifters perform better at high rpm's with a heavier oil (stability) but this may not be your environment.
I've tried 30/40/50. My temps [oil and coolant] were cooler with 30 and pressure was good, so that is what I use.
Try out a few

[DanEC]

Originally Posted by RET_COP

I would like to know why KC recommends 50w oil.

My take on this advice from Tony at KC is that it was probably targeted towards my particular motor and may not be the same advice they would give for other builds. In my case, I have a stock oil pump, Tony said they set up their clearances a little on the loose side typically, and summer weather was coming on.

Ironically they gave me a case of Joe Gibbs 10W-30 when I picked up the engine and I've run it as much or more so as the 15W-50. Hot, idle pressure in the summer gets down below 20 psi with the 30 weight which is OK, but I like the idea of a bit more. I suspect the heavier oil may be a good idea to keep my hydraulic lifters pumped up too in hot weather.