My 83 GS with 12a motor seems to have developed an oil pressure issue. If I hold a constant 4K rpm oil pressure will vary back and forth from just under 30 to about 60. This continues repeatedly as long as rpm's are constant. Seems to mainly happen when engine is good and warm. I know it's normal for pressure to vary with rpm's, but doesn't seem right if rpm's are constant. Could it be the pump? Seems like an oil pump should never fail. Bad seal maybe? Doesn't seem to use oil.

 

most likely its the stock sender/gauge, first gen oil gauges suck a big one. mine will read zero at some starts, 110 on others, once it warms up and i keep the rpm constant it'll drop/go to 60'ish, most of the time it hangs around 15 at idle and raises to about 45/55 when i'm on the road.

if you have access to an aftermarket one, install it just to check and make sure there's nothing wrong with your car.

 

Good idea. I'll check that out.

 

I assume you've already checked your oil level, right? Maybe clean up the connection on the sending unit and see if that helps. Did this start suddenly, or get worse over time?

 

Yes the oil is at proper level. I'll check out the sending unit first chance I get. Started suddenly not slowly.

 

turns out sending unit was loose.