High Mileage class of Motor Oils

[Diamondpilot]

Sudden Loss Of Oil Pressure - 2007 Chevy Silverado Vortec 6.0L - YouTube

Sadly I think it may be my pressure relief valve in the oil pump since multiply restarts when it is hot so far has brought the PSI back up. So far when cold the OP comes up and works fine but reading tends to go high with high RPM which would be expected if relief valve is sticking.

Per web the most common fix is changing out the sending unit. After we pull PSI with a manual oil pressure gauge the guessing can stop I guess. May do that this evening.

My neighbor that I always talk about on here had this very issue on a Caddy with a V8. I believe it they had to pull the motor or loosen it to get at it due to the close quarters.

Chris

 

[Gale Hawkins]

Hopefully we will not have to go there but if we do a 2WD with RWD will be cleaner up front to access hopefully. Since it occurred following an oil change that is more unknowns. We will get real readings soon but if it is the relief valve issue that may or may not give us clear info.

 

[clemsonfor]

some caddies are RWD.

 

[mikehaugen]

My neighbor that I always talk about on here had this very issue on a Caddy with a V8. I believe it they had to pull the motor or loosen it to get at it due to the close quarters.

now that is funny :laughing:

good luck, I hope it isn't anything too major.

 

[Diamondpilot]

now that is funny :laughing:

good luck, I hope it isn't anything too major.

This happened back in 03 or 04. He got it fixed and traded it on a new Honda.


Chris

 

[Diamondpilot]

Hopefully we will not have to go there but if we do a 2WD with RWD will be cleaner up front to access hopefully. Since it occurred following an oil change that is more unknowns. We will get real readings soon but if it is the relief valve issue that may or may not give us clear info.

Since its post oil change I would spend the $10 on a new filter first. You never know. Just because he uses quality parts that does not mean one bad one could not have slipped through. It could also be a bit of debris that made its way in during the oil change and its now causing the pressure relief to malfunction. I seen this happen on a Ford 8N

Chris

 

[Soundguy]

my 5.3 in my 00 yukon xl rattles a bit at start.. initially I thought it a problem. now near 200k later.. I guess not.

she's an oil drinker.. but runs.. has a few electrical probelms and 4wd issues.. but again.. the engine runs ok.

I run 15w40 in her instead of the oe ?5w30 or whatever is speced as a fuel saving oil.. her oil drinking has drastically stopepd with the 15w40. use to drink a quart every 1k EASY. that has dropped at LEAST by half if not more my last check. I used to have to check the oil every 3 weeks to make sure it was still in the has marked safe area. I checked it last week after exactly 1 month from oil change still in the top half of the has. I was quite amazed. the switch to 15w40 has been a few months of testing for me.. I decided to wait a few oil changes before I evaluated it..e tc.

 

[Gale Hawkins]

The 126,000 mile 2003 5.3L GM motor in the SUV Low Oil Pressure message and chime seems to have been fixed and the oil pressure gauge is rock solid at all times a day later.

Not sure what fixed it but I know the oil pressure sending unit that screws into the top of the block between the intake manifold and the fire wall was leaking oil. It is a 27mm brass nut with a plastic stem coming out of the top of it with three male connectors. It was leaking at the connection point between the brass nut and plastic stem and also had oil inside at the connection point.

Yesterday evening when I got it to the shop I could not duplicate the message and unstable oil pressure gauge readings like yesterday morning and days before when trying to start it after it was hot. Before replacing the sensor last night we pulled the PSI using a manual gauge and it was 35 at 650 RPM and 60 PSI at 3000 RPM. The oil was dino 5W-30 Castrol with 210 miles on it cut with 7.5 oz of Sea Foam put in 50 miles after the oil change. The Low Oil PSI message when starting hot first occurred about 25 miles after the oil change.

Clearly the sending unit had been leaking motor oil for a while as drops were found on the transmission pan. The oil with 210 miles on it and using the NAPA Gold filter was very dark which I expected due to having the Sea Foam in there for the last 160 miles. As posted earlier the oil change was made after the former dino oil had been driven 7500 miles and it was less than a pint low even with the leaking oil pressure sending unit so the engine is not ‘burning’ oil.

There is no way to say the oil pump pressure relief valve was a factor or not that was discussed in earlier posts. We did check the anti drain back valve that is part of the oil filter housing on the engine block and it was working correctly. While there was the normal ‘dry’ start engine noise until the filter filled and the oil pressure came up after changing the oil all was quite afterwards and the 40 miles since the oil change last night.

The main reason I used the Sea Foam (a normal practice on all of our engines before an oil change) in this new oil was to clean the inside of the engine before moving to Mobil 1 High Mileage 10W-40 motor oil due to the reported but not there now noise on start up. Last night we did use this oil and a new NAPA filter. After 10 miles hot the oil PSI is 40/60/75 at 650/2000/4000 RPM. Sea Foam is labeled to be use full time with a new oil change BUT one must monitor and change early if the filter is not able to keep the oil relative clean.

Mobil states in BOLD to not run the first change to HM Mobil 1 > 3000 miles the first or even second oil change when moving from dino oil due to sludge creation might block oil flow. The Sea Foam crankcase flush was to help clean the block BEFORE moving to Mobil 1 from dino. I will monitor and will do the first change at 1000 or 2000 miles if the oil goes black one this first Mobil 1 usage. I will stick with Mobil one I expect since it is a tad cheaper than Rotella 5W-40 but not sure which weight yet.

Side note: This week I learned/relearned more about zinc content or the lack there of in motor oil today. Since Rotella Synthetic 5W-40 is also gas engine rated I still plan to use it the old Ford/Chevy big block engines and the JD and MF old 60 HP backhoe and tractor but at a 50/50 blend with Rotella 15W-40. Gas engine rated motor oil is limited to 800 zinc level but the Rotella 15W-40 dino level is 1300 so more or less I will have a zinc level 1050 and 10W-40 weight which I prefer for flat tappets. This blend will be of the same brand of oil while that may not be necessary.

 

[Diamondpilot]

Glad it was a easy fix.

Chris

 

[Gale Hawkins]

When we found oil all around the area we got excited.

Working blind to some degree at the firewall and tool requirements made it quite a chore but nothing like pull oil pan, etc.

If I ever had the intake manifold off of a 4.3, 5.3 or 6.0 GM engine of this generation I would replace the oil sending unit for just the $50 part cost. That was the first one I had fail however but per the web it does happen giving the no oil pressure warning.

Replacing external parts is always easier than internal parts.

Why it happened right after an oil change I will never know but it sure added to the confusion of the cause.