I've got a high milage 350 in my truck and since I bought it, about 10,000 miles ago, it has had about 5 psi oil pressure at idle; that is if the guage is linear and accurate. The pressure tops out at about 35 psi when the engine is cold, but that is what the pressure is regulated for; I get 30 psi when I'm driving. I am starting to hear and feel the crank walking in the bearings at idle and what I want to know is, can I fix this by replacing the oil pump with a high volume unit, or do I have to replace the mains. As the oil pressure picks up with rpm, the motor runs smoother and smoother, all of the way to the redline. I know I should just rebuild the motor, but I am on a college student budget of 0 dollars right now, that and it runs like a champ, no smoke or anything. Just a little positive crank case pressure when going up long steep hills at 65 mph - thats with 3.73 gears and no overdrive too.