Pontiac Repair: 1998 pontiac bonneville, oil pressure gauge, oil filter housing

Question
I have a 1998 Bonneville the oil pressure gauge has started bouncing between 80 pounds and 20 pounds.When traveling at top speed the pressure gauge reads around 40 pounds, but when i slow down it drops down to 20 pounds. I have had the oil sending unit changed but it hasn't helped. The engine is not making any noises so I don't believe it is hurt. What could be causing the gauge to act like this?

Answer
change the oil filter and see if that helps.if not there is a relief valve behind the oil filter housing that may be stuck open a bit.sometimes removing this and cleaning will help.then if it still reads low the engine may have worn bearings and just cant get the pressure.i would also recommend purchasing a new manual gauge and rig it up to check it yourself bipassing the factory setup.just for testing purposes to see what you are getting cold then after the engine warms.my firebird holds about 60 constant psi. exept for really hot days its down a bit.