5.3 High mileage oil

[ken vanderburg]

hello from Northern ,Alberta ,im 79 yrs old retired small engine mechanic.
i have 05 GMC 1500 4x4 with 495,000 kms on it ( 300,000 miles,) got it original 85 yr old owner 3 months ago who Never changed the oil,changed filter and added new oil every 5000 kms.. it clicked when i first got it..so i bought a 5 gal pail of cheap chit 10-30 from Wally world..after 3 changes,,motor runs very quiet, but 20 lbs on oil pressure at idle..40 at highway speeds, should i use heavier oil and or additive.my HD mechanic friend recomends 15-40 in everything or add Lucas motor conditioner.. what do you think.?

 

[hemitom]

Hello and welcome.
I would be interested in knowing what he used for oil ?
Alberta winters COLD i would run something lighter ! summer 10w30 is fine or try the 15w40 won't hurt.

 

[MParr]

Are you using the gauge in the instrument cluster to monitor your oil pressure? Those gauges aren’t really the best. 15W40 might be a little thick for your area. Just run a 10W30 or 10W40 high mileage oil and call it good.

 

[ken vanderburg]

Hello and welcome.
I would be interested in knowing what he used for oil ?
Alberta winters COLD i would run something lighter ! summer 10w30 is fine or try the 15w40 won't hurt.

he ran new Cat D8, so probably used same oil..what ever that is..and had a heated garage when at home.

 

[ken vanderburg]

.GM dealer shop foreman says to not worry about it,.its a LS thing.

 

[Tortuga]

It’s fairly common for an o-ring on the oil pickup tube to go bad on higher mileage GM 5.3L engines. This allows air to bypass the pickup and results in lower oil pressure.

I’ve heard you can test this by overfilling the crankcase by a quart or two. I guess in theory that would bring the oil level up to the bottom of the pump so that the o-ring couldn’t suck air if it was bad. I wouldn’t run it with that much excess oil for a long period. Maybe try to overfill it right before a scheduled change and see if the pressure changes.

At 300k miles, you might as well replace the whole pump if the o-ring is bad.

 

[Tortuga]

There’s some discussion of the o-ring issue in this thread including pictures of a defective and new o-ring, and the location of the o-ring on the pick up tube, which is well above the oil level.

Post in thread '5.3& 6.0 GM trucks losing oil pressure PF48E'
https://bobistheoilguy.com/forums/t...losing-oil-pressure-pf48e.286907/post-4718129

 

[Merek]

There’s some discussion of the o-ring issue in this thread including pictures of a defective and new o-ring, and the location of the o-ring on the pick up tube, which is well above the oil level.

Post in thread '5.3& 6.0 GM trucks losing oil pressure PF48E'
https://bobistheoilguy.com/forums/t...losing-oil-pressure-pf48e.286907/post-4718129

His truck uses the PF46E which has standard threads, the newer 2007+ NBS uses the PF48E and is metric so make sure you don't get the two mixed up. The o-ring on the oil pickup tube can definitely fail and will allow it to suck air and cause the oil pressure reading to fluctuate. There are lots of people on here that use Mobil 1 0w40 in these engines. I'm using Shell RGT in mine and typically run the PF46E but currently using a Fram Ultra XG3506 to help cut the number of filter changes down. You can run the PF61E as it's the same just slightly longer.

The gauge cluster could be suspect, GM had a recall on those stepper motors, however my speedometer stopped working just after the mileage they warrantied it for, I read that most likely they would've repaired it under warranty being that close but they would've only fixed the one that was broken and not all of the motors. I ended up shipping to someone I had found on eBay who replaced all of them for not much money. GM's warranty on the cluster was a joke, they went by mileage on the vehicle so there were tons of vehicles out there they didn't have to repair on their dime. On mine the gauge cluster warranty expired at around 75k but it stopped working just after 80k miles, I don't remember the exact years but mostly 04-05 were the worst ones.

 

[ken vanderburg]

my original dash works except the digital display doesnt, so i bought a supposed rebuilt dash fromE bay,it was the same,,got refund,so my son started collecting 99-06 trucks for body parts,,have dash with half my mileage that kinda works,,can only see the digital at night. like to send my original dash to a honest repair place,, and ideas where to send it?

 

[Merek]

There's a video I've seen on YouTube where if the cluster is basically displaying gibberish, changing between languages, etc... you can remove the cluster and then run your fingers over the back of the circuit board, something about they generate static electricity and they don't have a way to discharge and by running your fingers over it can absorb the excess out of it. I had that problem when I haven't driven it for awhile like a month and the system was drained out, I got lucky and just had to jump start it but most everything else seemed fine but the cluster was having that issue and has never done that before. I reached out to someone else on YouTube who repaired these clusters but never heard anything back but then I found that other video, haven't tried it yet but seems so far that mine has resolved itself.

A website you can try is https://www.gmgaugerepair.com and he's on eBay as well. I'm going to use them whenever I can get around to having the transmission temp gauge installed.

It's a lot easier to use the original cluster as they are programmed differently by which engine and transmission it has. I've heard of others found a replacement cluster and had to goto the dealer and have them program it to the vehicle.

 

[ken vanderburg]

no need to go to dealer to reprogram a used cluster,,,New one yes, But New one from dealer is about $800 plus hour to reprogram.

 

[fleetguy1984]

Ya most common issue on the 03-07 Full size SUV/Classic body pickups they had those stupid step motor issues on the cluster

Had to have it fixed on my old 04 Escalade and 03 Silverado

 

[FastLane]

When I had my oil pan off I changed that O ring. Mine was slightly deformed. I’m sure it was still working fine. I had 200,000 kms on it when I changed it. I’ve only ran synthetic 5W30 in my 4.8.

 

[userfriendly]

How many kms a year are you going to put on the truck? One oil for year round is 0W40, either Duron, T6 or Delvac. If you can do seasonal oil changes, 15W40 works well for summer use in 5.3 and 6L Chev and GMC trucks.

 

[PontiacHO]

hello from Northern ,Alberta ,im 79 yrs old retired small engine mechanic.
i have 05 GMC 1500 4x4 with 495,000 kms on it ( 300,000 miles,) got it original 85 yr old owner 3 months ago who Never changed the oil,changed filter and added new oil every 5000 kms.. it clicked when i first got it..so i bought a 5 gal pail of cheap chit 10-30 from Wally world..after 3 changes,,motor runs very quiet, but 20 lbs on oil pressure at idle..40 at highway speeds, should i use heavier oil and or additive.my HD mechanic friend recomends 15-40 in everything or add Lucas motor conditioner.. what do you think.?

My 5.3 with 80k has the same oil pressure. In my opinion that’s normal oil pressure.

 

[nascarnation]

My old 4.3 with 160,000 miles has that same 20 psi idle 40 psi @2000 rpm oil pressure and seems to just chug along fine on 5W30.