Oil pressure erratic
 

Went to cruise last night. Got going down highway about 2800 rpm for 15 minutes, temp was 180, outside temp was 95. . Looked down and had 15 # on factory gauge on 66 GTO. Motor has been together for 12 years, just driven normally. Normally runs 50-60 at highway speed. About 5 miles later needle jumped to 60 # and stayed there and acted normal when slowed rpm to an idle, 30 # at idle. Did the same coming home. This morning started in garage and had 60# cold. 30 w oil & ac delco filter. any thoughts

Given no other symptoms, install a mechanical gauge and watch for the factory gauge to do it again. If it does, what does the mechanical gauge read?

I'd guess a piece of trash had the oil pressure relief ball held off its seat. Then got washed on through and returned things to normal.

Clay

You should think about getting a switch to Tee in like a SW 76073.
This comes set to 35 psi and has both normally open and normally closed contacts on it.
You can wire it to light to warn you when pressure goes lower then 35 psi, in fact it’s adjustable, so you could set it for 45 or 25 if you like .
This switch can also help you trouble shoot what’s going on now if you have a volt/ohm meter you do not even have to wire it up to see if your current oil sender is screwing up or not.

Have you checked your oil level? If it's a little low the quantity may be low in the pan at higher rpm and isn't returning quick enough. Also do you know that the pickup screen for the pump is close enough to the bottom of the pan? If it's a little too high a low oil level would definitely cause this issue.