Oil Pressure Gage?
 

Wondering what could be wrong with this. On the cluster it goes from 0-100. It usually varies alot at which spot it stays. Sometimes pressing the gas with make it drop and letting off will make it rise? Anyone have any ideas? And would I just be better hooking up an aftermarket one?

When was the last time the oil was changed? The oil filter could be clogged. Mine did that for a couple days and changed the oil no more problem.

thats a nice car that deserves a nice set of aftermarket gauges

Could also be the sending unit.

Not sure when the last time the oil was changed. But after my 1400 mile trip it's getting changed tomorrow. So we'll see if it's that. Well it's already got 2 a pillar gauges for air/fuel, one for each bank. But I'm looking at getting the 3 center mount unit from Autometer with Oil pressure...hmm..and not sure what else.

How many miles on the motor? And yes that car is nice! A bad sening unit does that, or a bad ground, so does low oil pressure. drain it, refill, and drain it again, if its real dirty... I like that Royal Purple racing oil... 5 bucks a bottle but awsome stuff. Lucas oil treatment works good too, just not the whole bottle. Half the bottle works great.

Well, there are now 76k miles on the motor. When I get a chance tomorrow I'm going to have to check it out. It's funny though. I noticed that sometimes it doesn't seem to jump, but like tonight, on a cool night, the range barely changed.

Probably the sending unit. For some reason, they don't last forever. I've replaced mine 3 times.

Just get an autometer mechanical and forget about it. You won't be sorry and your gauge will be accurate. Until then, change the oil, filter, and sending unit.

Mine kinda does the same thing, At nite the oil pressure seems higher, My buick does that too, but the pressure is the same either way. change the oil, flush it, and get a new sending unit.