I've had a knocking sound coming from my passanger side head that has been diagnosed as rocker "chattering" due to my high miles...
I was running 10w30 and was told that its too thin in this 90 degree future summer weather were having here in San Diego
I was told I should switch to a heavier weight...
20w50...
I've had mixed reviews on whether I should use this or not...
I though I had a tick in my passenger side head too. It turned out to be a bad donut gasket in between my stock manifold and H-pipe. The tick was gone after I got my exhaust done. Check the gasket out before you let some creep mechanic rip apart your motor, you might not even need that. Cobra's are supposed to use 5w30 no matter what the conditions. 10w30 and higher, is too thick, and will starve your heads of oil. How long have you been using the 10w30? IF it is the rockers ticking, that might be why they are because too think of oil. Try the exhast first though.
try runnign 10W-30 first with lucas oil stabilizer. if that doesnt wrok, teh best dino 20W-50 i found was quaker state peak performance. def. dont use 20W-50 when it gets chilly out though
Try using 5-50 synthetic. I've run it since new in a GT-40 crate motor with 240k miles, and cylinder pressure and leakdown are well within factory specs. Still have great oil pressure, too. It's a little expensive, but I think it's worth it.