I went ahead and put the 0W-40 synthetic oil into my 1995 Grand Am four
cylinder.
As expected the hot idle pressure went up. It went from about 12 PSI to
about 20 PSI. So I achieved my goal. The problem is that all other times
the
pressure gage is pegged past 80 PSI. A mechanical gage shows the pressure
about 120 PSI and the needle shakes widely.
A responder to my original post suggested that the cold maximum pressure
of
80 PSI seemed a bit high. He was onto something. I am guessing that the
pressure relief valve is sticking. I wonder if this was causing the low
(12
PSI) at hot idle with the 5-30 oil. Looking at the manual, it seems like a
time consuming job to get to the pressure relief valve and that might not
be
the problem. The car is in good shape and I want to make it last a lot
longer.
I don't know what to do. Any suggestions?
Thanks, Scott
