Originally Posted by Peter Tremonti

I just started having a similar issue with my 2005 5.3 Suburban. I noticed a ticking last week at a red light while driving to work (~20 minutes of driving). It wasn't there when I started in the morning and went away by the time I got to work ~10 minutes later. The tick went along with engine speed but I had oil pressure between 40-45psi while I was driving normally between idle and 2000rpm. Anyways, I put half a can of seafoam into the oil and drove it for a week ~100 miles and changed the oil with my usual Rotella T6 5w40 and a new Delco filter.

Now that I've been paying more attention to the oil pressure I've noticed now when I first start up in the morning, my oil pressure stays at 35psi and seems to try hard to get up to 40psi but won't make it there even at 2000rpm. After driving for 15 minutes or so and letting some heat into the oil the oil gauge starts to act seemingly normal. At idle the pressure is right below 40psi. At 1000rpm, the oil is at 40psi exactly according to the gauge. 1500rpm gets ~45psi and above 2000rpm it's between 50 and 55psi.

The most confusing thing about this is why it acts reverse of every other car I've driven where the pressure is high when cold and lowers when warm. WTH is going on with this thing?

Originally Posted by Justinshane96

First thing I did was is pull the oil sending unit out and put a manual gauge on it and I still had the same issue. My truck was an 03 so I didn’t have a screen underneath the oil sending unit which I’ve heard they will get clogged up.
I had a bad lifter tick but after I replaced the oil pump it went away and truck ran great. The o-ring on the pick up tube could be damaged or the screen on the pickup tube in the oil pan could be clogged. I replaced the pump without removing the oil pan it’s pretty easy there are some videos on YouTube that will help out a lot