My 91 RS has 116000 miles on it. Until recently my oil pressure gauge has been pretty steady between 45 and 60(ish) psi. Lately though it has been very erratic. When hot, at idle, pressure drops to 30psi; yet when the engine is under load, pressure levels out at 55(ish)psi after an initial jump to well beyond 60 psi.

I have read some of the other posts about drops in oil pressure (0 psi) and am very concerned.

Could it be the oil pump? the valves? the bearings? the gauge? sending unit?How & what exactly can I do to diagnos it's problem? I have checked and I see no metal particles in the oil.

Really don't want to trash the motor... would prefer to fix problem now!

 

dont worry too bad man..if the cars not smoking or pinging or knocking or overheating have no fear.......mine is doing the same thing and it still runs like a top....check the connection to the sending unit (the sending unit is above your oil filter screwed into the oil filter adapter) if the connections look fine its probably just the sending unit....thats where i would start with a new one.....I am fixing to do an engine swap so im not too worried about mine at this time cause when i swap i'll be using all new parts anyway.....but try that first and let me know.....hope this helps

 

GM oil pressure sending units are very commonly found to fail or act erractically.

 

I know this all too well. I have an 85 Iroc with 26,500 miles on it (original), did the same thing, and they just replaced the "sending unit" for me. Works fine now.

 

I will replace sending unit this weekend as a first step. Autozone stocks 'em for $28. Sounds like a good place to start. Thanks for the help guys!