I have a 2000 Camaro V6 3.8L and the oil pressure gauge needle is a bit over the mid-mark on highway. But is below the mid-mark in city streets. But the engine has a bit of a kick to it (very very minor misfire, may be a bad cat P0420).

But on idle, the oil pressure gauge needle then moves from both positions (slightly below mid to slightly over mid) but no where near the dangerous red.

What is making it move like that? It's never done that but could this be related to the P0420 trouble code? Thanks!

 

well you could have a leak causing your loss in pressure

 

You saying it moves up and down when at idle? Do your rpms do the same thing at idle?