Hey guys, I'm sure there has been other threads about the 5.3 Oil Pressures, and I have searched, but have not been able to find one that addresses what I am experiencing.

1st, I am the only owner of my truck.
2nd, I have maintained it religiously.

The engine is original and has @205k miles.

Since I bought the truck, the cold start oil pressure - at idle - would hover around 60. As the engine warmed up, it would naturally drop to around 40 at idle. Drive er down the road and pressure would fluctuate between 40 and 60 depending on rpm. Did the same for 11.5 years.

About 6 months ago, I noticed the cold start oil pressure - at idle - would never rise above 40, so a decrease of about 20. Increase the rpms, it would stay at 40......UNTIL it warmed up - at which point it would do what it had always done, fluctuate between 40 and 60, depending on RPM.

Today, I had the oil pressure switch replaced and now it actually a quite a bit WORSE!

At cold start up idle - 35, warm engine idle - 35. Accelerated rpm(normal driving) never gets above about 45.

I did get a little aggravated driving home and at about 25 mph, floored it such that it would shift down and increase the rpm's. Oil pressure went to 60 until it shifted, at which point, it went back to about 45.

There is no oil consumption. No knocking.

Do I have a gauge going bad? Oil pump going bad? Electrical problem?

This kind of stuff drives me crazy.

I want it to do what it has done for 11.5 years. Am I crazy?

 

35 PSI isn't bad for a 200K plus mileage and is plenty. My wife's 03 with 95K stays around 40 warmed up and starts cold at only 45-50. I wouldn't sweat it.
Have you changed the oil brand, viscosity, oil filter brand or anything lately?

 

^For probably the 1st 120K, I used synthetic only with delco filters, then I switched to conv. oil for about the next 60k or so. Have always used 5w-30 for both syn. and conv.

I switched to conv. because I didn't like the price of where syn. went, but I decided it was worth it a year or so ago.

Currently, it's got Mobil 1 5w-30 with a Mobil 1 filter.

I guess my main concern is why the oil pressure doesn't move when the engine is cold and rpm's are increased.......

 

I had the same problem with my 02 1500 Z71. It has 150k on it and i was running con. oil always ran 10w30 here in ohio and K&N oil filter. The oil pressure did drop so i changed to synthetic at 146k and said the heck with it changed to Royal Purple with K&N Gold oil filter. Now im running 62-64pis on warm up and 60psi when im driving but when i "FLOOR IT" im running 80psi lol... Now that im running RP the fuel knock/piston slap has gone away. IMO its worth the 75 dollar oil change every 6k miles. Hope this helps some what. Have a good one.

 

Which RP did you use? The standard API Certified or the HPS?

Looks like the HPS is for High Performance or modified engines....

5w-30 or 10w-30?

Thanks.

 

Im using the HPS 10w30. Its like 10 bucks a quart...

 

Check the pressure of the oil pressure and check the oil pipe if there is any leakage or not.