Low oil pressure in my 94?

[94OldRed]

Recently I've started to notice my oil pressure dropping further and further. On a cold start up I have good pressure, right at about 40 or a few notches above. But once the truck starts to warm up, it drops down to maybe the first notch or two. Accelerating back up to speed I have good pressure, but once I reach cruising speed it's down again. Cruising at 70 on the freeway, like I said before, it's sitting 1 or 2 notches above the red. Now I just rebuilt this motor 10k miles ago, so it's still brand new. I never did replace the oil pressure sensor during the rebuild, Could the sensor be going out?

 

[SCOTTYINWV]

Rule of thumb is like 10psi per 1000 rpm iirc. Sometimes the factory gauges cannot be trusted though. Mechanical may be the way to go if you are worried about it.

 

[Rusty Nail]

Are you using the weight of oil that the engine builder recommended?

 

[jrollings]

I'd hook up a mechanical psi tester and go from there. Compare the two. Hopefully your sending unit is just biting the dust and its not your main bearings.

 

[454/4X4]

My 95 K1500 has a Crate 350 with all new sensors, senders, etc installed at time of swap...about 35K on it all, I get about 65psi on startup, and 30 idling in gear, 35-40 in park, hot...

At around 3500 miles on the oil change, It will start to fluctuate both while driving and while stopped...such as dropping to about 20psi at a light..and going up to 55 if I touch the gas at all.

If I change the oil...fresh 10W30, its back up...no more fluctuations. Im not easy on it, I tow some, I do alot of WOT pulls with the engine bouncing off the redline going into 2nd...it'll take it, but the oil doesnt hold up to longer changes...

Something to consider...may need an oil and filter change?