I have a '85 Chevy S10 with a 2.8 L v6 and a 5 spd manual trans. It has 157000 miles on it. I think it is time to replace my main and perhaps rod bearings. The motor will only make about 10 psi oil presure at idle after warm up when the air outside is around 70 degrees F. and about 30 psi while the truck is going 65 mph in 5th. I am using 10w40 oil and it does help some but not enough. How high should my oil presure actualy be?