Hi Everyone,

I recently bought a 2004 Silverado 1500 with the 5.3L Vortec. It has 250,000km. Overall the truck is in great shape, however I am having an issue with low oil pressure. When I first start the truck, cold start, I have about 20psi on the gauge. After warming up however the oil pressure drops to 0 at idle. Give it some gas and the pressure jumps back up no problem. Everything I read said change the sender, did that, no change. Also read that it could be the o-ring on the pickup tube. I parked on a steep downhill incline and there was no change, also it threw a p0322 code out of nowhere. I am stumped. Anyone have any ideas? I was thinking about throwing a quart of ATF in her and letting run for 10mins, then change the oil. Thanks for the help guys, I'm fresh out of school and trying to get a renovation business off the ground, so any tips to save some dough are much appreciated.

 

Have you changed the oil in it recently? I know when I got mine and put the oil it calls for in it, my oil pressure went up.

 

What pressure do you see all warmed up at 1500-2000 rpm?
Do you know weight of oil in there now?
155k miles if my math is right

 

I would try a heavier weight oil and see if that helps. 155,000 miles isn't that much if the truck was well maintained.

 

Thanks for the responses everyone. The oil pressure jumps back up to 20 whenever the truck is between 1000 and 1500 rpms at temp. I'm not sure what weight oil is in the truck, I suppose I should just change it. When you say heavier weight, I'm assuming that we don't care about the winter weight, so a 5w50 then? What are your thoughts on using ATF or another kind of additive to try and clean it out before I change the oil?

 

20 psi is also low. At 2000 rpm my truck is at 37psi. I wouldn't try and clean it as that might make it worse. If things were clogged, it would make the pressure higher not lower. I would try 20w50 oil. If that doesn't help then your next step would probably be to change the oil pump and see if there is sludge in the pan which could cause the problem also if it is up to the oil pickup.

 

Are you reading your oil pressure off the dash gauge? If so you may want to try checking the oil pressure with another gauge. The dash gauges can be off.

 

I have a 2009 Silverado 1500. At start up I have about 50 psi oil. After warn up and in park, I have 34-40 psi . In drive and at around 50 mph, I have 30 psi and sometimes less. I changed the oil to a 5/40 synthetic. The problem still continues. Can anyone tell me if this is normal?

 

it really depends on the millage of the vehicle. but i know gm used to say 10psi per 1k rpms is "ok"