Bob,According to the DD Field Service Manual, (sorry, I don't have the service manual handy, it's packed away), for a 4 valve 6V53 you should only see 40-60 psi oil pressure between 2200 and 2800 rpm.In my experience, 53's, along with being noisy, had the same oil pressure at idle that the 71's had.. usually around 5-20 psi after they were well broken in. If you are seeing more than that with your digital gauges, you may have an incorrect sending unit and gauge set, or a bad ground at the dash or engine, or, and this is important... the bypass on the oil filter housing may be hanging up. As was mentioned in a previous post, stick a mechanically reading gauge in the back of the engine compartment to make an accurate reading of what you actually have going on.You may also want to add a mechanical coolant temperature gauge and a mechanical fuel pressure gauge. These allow you to come back to the engine compartment and see what is actually going on with the bus.Good luck,Dallas