[FirebirdDave]

This is to follow up on David Jones cam failure thread. It has been several years but I have had similar experiences with cam failure in years past. One thing I have noticed over the years on all the hotrod pontiac engines I have run is they tend to have a lot of valve train noise when the are cold.
Getting away from the valve lash issue for a second I have done some experimenting with multi viscosity oils and have made an interesting discovery. Years ago I ran 10w40s and 2w50s. More recently in my latest engine I have used 10w30. In the last oil change at a friends urging I switched to 5W30. Now I have been running Mobile1 since this engine was put together and continue to this day to use Mobile1. Also I have had the valley pan off acouple of times in the last year and every thing continuses to lookk good. But here is the interesting part. Even with the 10w30 I had valve train racket when the engine was cold. When I switched to the 5w30 the noise decrease was substantial. My warm idle oil pressure doesnt seem to have changeed much if any. I ususally see about 18-20 psi at a 800 rpm idle comming off the interstate, and about 50-55 at cruise at 1900rpms. The cruise oill pressure didnt change either. So far I am very please with the thinner cold number in my mobile1. Obviously when I change the oil in the spring I will probably change back to the 10w30 but so far the 5w30 has been a pleasent improvement for me.
What do the rest of you think, has any one else tried such a thin oil in the winter in a 455 and what was the result?