Just got this 96 gmc Sierra its got the 4.3 vortec tbi motor, now what I've noticed is the oil psi gauge reads low, now befor i get started I'll add that with the key off I check the gauges I notice the oil psi is at 20 or around 20 psi, I thought that was weird cause key is off it should read 0 correct? But anyways I start it up from cold and oil psi reads 20 to 25, I drive around until operating temp and it sits around 20 to 25, sometimes when I come to stops it will drop to about 18 to 19 little under 20, usually hovers around 20 no matter what it seems wtf is up with this, I like to believe the gauge or sender is messed up? Can any one shed some light on this? The motor seems to runs smooth and sounds healthy, I have no knocks or ticks from what I can hear and the oil seems clean as it should since I changed it, I'm not low cause I constantly check oil on all vehicles I drive

Best way to eliminate the oil pressure gauge is to remove the stock oil pressure sensor and install a mechanical oil pressure test gauge. Start the engine and verify the pressure. If its higher than 20psi and not fluctuating, then your existing sender should be fine and we can probably just assume your instrument cluster is bad.

i dont know if anything is wrong the gauges arent returning type. they just stop were ever you turn the key off

They should at least "zero" when the power is turned on.

yes but he said with the key off. it doesnt sound accurate though, should be over 40 or so cold then come back to 20'* warm

He never did say what the gauge said when power is turned on(engine off)

With the key in the on position with it not started, it will go down to zero, but I noticed the gas gauge likes to drop to zero when I come to stops, and the temp gauge seems screwy even, I'm starting to think the cluster is just goofy but I could be wrong cause this is the only gmc pickup I've ever owned, I notice the oil psi will move about 2 or 3 of them lines up or down and that'* it, when cold I slowly rev it to 2000 rpms and it doesn't seem to move up higher than 1 or 2 bars above 20,

the gauges are more of a rough estimate on all gms. my temp reads 165 when its 195. if you want accurate numbers you can get aftermarket gauges or a obd2 interface like scangauge or torque pro for android phones

I did notice there is a tick on the passenger side but could be from the manifold to y pipe, I felt around there and noticed a leak, otherwise the motor sounds good, I rev and hold on 3k rpm and the oil gauge doesn't seem to go past 25 and at idle it never goes below 18 or 19,

The previous owner also redid the intake gasket, he said when it went it over heated, perhaps coolant got down there and destroyed some bearing causing low oil psi??? Idk I've never dealt with this, maybe I'm just fretting over it to much, I've been driving it around a lot lately and don't notice anything different about it