High Oil Pressure
 

I have read several threads on oil pressures in flatheads, and need to confirm if I am making the right decision, as to the grade of oil I am using. I have a stock 59AB in my '46 Coupe, running Shell Rotella 15-40. When at running temp, the oil pressure is 20 psi at idle, and 60 psi at cruise. A few comments on previous posts, say that high oil pressure can damage the bearings. Is this something I should be worried about? I am thinking of changing out to 10-30 grade, to see what affect the lower viscosity will have on the pressures. Thoughts and comments are appreciated, even if this old horse has been beat many times.

Re: High Oil Pressure
 

I believe that 55 psi is the proper high pressure. That's what I have on both of my engines. The fact that you have 60 is probably not a problem. It may be caused by running the heavier diesel oil. In my opinion, a switch to a lighter weight oil intended for automotive use would be a good move for several reasons. As long as adequate pressure is maintained, the lighter the oil you can run the better.

Remember the old rule of thumb "10 psi per 1000 RPM".

Re: High Oil Pressure
 

While not too high, I would switch to 10W - 30. Been running that for many years.

Re: High Oil Pressure
 

Your oil pressure reading is fine don't lose any sleep worrying about it.
Ronnieroadster

Re: High Oil Pressure
 

Your pressure is fine. Stick with the 15/40.