I have a 2003 lq9 118k that i swapped into my 2006 silverado 1600, Truck has 212/218 high lift cam and pac springs, When I start my motor after truck has sat a day, oil pressure is about 32lbs, I noticed it was low to my standards, I let it idle for a bit and take it for a cruise, after about 5-10 minutes of driving the oil pressure creeps up to about 45psi at 1500 rpms and if i stop to idle its in the upper 30s, Could this be an o ring issue or just a bad sending unit?

I used the sending unit from my 2006 l33 engine and never had the issue. I also tried new oil filter different brand and no difference.

When motor is started cold i can rev it to say 2000rpm and psi does not move from 32psi. I dont dare rev it any higher incase it is an internal engine issue not just a sensor.

 

it does sound low, cold should be around 60 psi i think.
what weight oil are you using ? brand of oil ?

 

Using Amsoil 5w30 hdd oil. Napa gold filter. No difference between it and the 5w30 Pennzoil and purolator that were in it.

 

try a 10-30 and see what it does, I moved up to the 10-30 Mobil 1
last year when i heard guys having oil probs with 5-30.
I only use AC Delco filters. where are you taking the readings from ?
is it a factory gauge or aftermarket ?

 

Factory gauge.

 

I just spent $65 on the oil in it less then 100 miles ago. I'm not going to dump it and run 10w30 going into winter

 

I am going to try another sending unit. My friend who sold me motor never had this issue.

 

was the oil pickup tube ever removed when you did the motor swap? cuz if so the o ring might not be seated properly giving you low pressure.

 

Just swapped engines nothing else. Cam was already in

 

Could possibly be some sludge in the pickup tube screen