My oil pressure does tricks???

Oil pressure goes down when revving???

89 xj 4.0, 180,000Miles

So, i thought this was odd. I just changed my oil to a 20W-50 and added some Lucas. Thought id run a thicker oil for when i get it off camber. Anyway, i started it today (about 27 degrees here in GJ Colorado) and my cheap aftermarket gauge took like 5 or 6 seconds to move up...when it did it went slow and heres the trick. Once it got up to like 40, i revved the motor and it went down!! when i got off the throttle it went up...did this for about the first minute then it started doing what all good little engines should do and when i revved it, the pressure went up. So do you guys think its:
A: nothing to worry about because aftermarket gauges suck(but this one has never acted up before)
B:You used too thick of oil and should change it ASAP
C: Your motor is on the verge of death and is trying to tell you to let it die peacefully

???

Its B, and if you don't change it to something more suitable to 20 degree Colorado wx, then C will soon follow.

The reverse oil pressure is your oil pump starving for oil because the oil mixture you have concocted is too thick to be picked up quickly enough. Try something more conventional like 10w-30 or better yet, a 5w-30 with no extra stuff in it. You might also start thinking about dropping the pan next spring and cleaning up the pump intake. It sounds like it could be partially plugged up which adds to the problem.

A good synthetic blend is a reasonable compromise. I run Valvoline durablend. It doesn't thicken too much in really cold weather. 20w-50 and Lucas might work on an old motor in the summer, but you will cause more wear over one winter with that than you have done in the last 50K miles. As long as the pressure says above 13psi at an idle, don't worry about it.

well, heres an idea that just came to me. Do you think its so thick that the pump picks it up and sends it to the top of the motor and it dosent have time to drain back into the pan quick enough to refil the pan. So its sucking all the oil up and starving at higher rpms because the pans almost empty?...either way, i think ill change the oil soon.

what do you guys think of the wal mart cheapy super tech oil?? I was told by an engine guy that its cheaper but actually has the same lube properties as the pricey stuff??

any other thoughts?