Short vs long term fix for low oil pressure on 6.2

[WeekenderNutJob]

I have a 6.2 on a 2008 Denali. Pretty sure it has VVT. Trying to diagnose a low oil pressure on 232,000 mi . No knocks no check engine oil light. I've installed AC Delco sending unit and screen. Still low. Using a wix gold filter and 5W30 high mileage synthetic. Warm Idle pressure is at maybe 10 or less maybe even as low 7 PSI.... which seems scary to me. My next best guess is the pickup tube o-ring or bypass relief valve or the pump und spring. Which fom my understanding all require the removal of the pan. I have a all-wheel drive and so it's going to be a pain to do for a bit and I'm not going to get to for a month or more.

What would you do for a short-term fix? Thicker oil like a Lucas oil stabilizer? I've also read that adding an extra quart or two of oil may temporarily put the o-ring under enough oil that it actually sucks, if that's the issue. I don't know much history on this car. I just purchased it.

I've read posts for about the last hour and I'm not finding a good all-in-one, while you're in there fix this also type of thread for dropping the oil pan. Does anybody have a good list?

Assuming it's going to be a month or two before I can get to it. What are the best short-term fixes?

Oil pressure when it's driving seems to be around 25-40. It mostly just drops really low when I'm sitting at a light. Oil pressure climbs basically about 10 psi for each 1000 rpm.

 

[B-train]

You are probably dealing with a cracked and degraded o-ring on the pickup tube. You are also most definitely dealing with oil loss from the block off o-rings under the top engine plate (flat plate under intake plenum). This year doesn't have AFM, so the oil passages are blocked off with about 8 o-rings or so. These get squished and hardened from years of heat and pressure. They will then spray out and you will lose pressure at idle. This does put more oil in the cam area which isn't bad, but potentially starves more critical components.

To do this job isn't too bad and will take a proficient person a couple hours. It's a dry intake, so easy peasy. Just buy new intake gaskets and maybe valve cover gaskets if they look leaky. The o-ring kit is available from advance auto and I've had good luck doing 3 sets of then now over the years.

The oil pan isn't too bad, it can be done on your back in a garage. It will take a proficient person about 5 hours to do in this manner. Replace the pump pick up o-ring, clean it up good, and reassemble with a new gasket - DON'T use a cheap silicone for the corner joints - buy GM or equivalent.

I know some people have had oil pump issues, but personally I've never experienced it. My guess is that it's fine and is just not able to keep up with the loss of suction and fluid loss. You could try running more oil in the pan. Again, never did it, but it may help you narrow down some things. Just be aware that overfull oil can froth up and then provides no protection. Oil pumps aren't air pumps.....

Since you will be dropping the front diff, carrier, and frame section make sure you inspect the carrier bushings. These tend to wear out with that many miles and can lead to annoying clunks under your feet. My advice would be to just buy new GM and bolt it in - forget messing with the aftermarket press-in replacements. They are a total PITA and not the same quality - been there and got the participation trophy.

 

[B-train]

I have a 6.2 on a 2008 Denali. Pretty sure it has VVT. Trying to diagnose a low oil pressure on 232,000 mi . No knocks no check engine oil light. I've installed AC Delco sending unit and screen. Still low. Using a wix gold filter and 5W30 high mileage synthetic. Warm Idle pressure is at maybe 10 or less maybe even as low 7 PSI.... which seems scary to me. My next best guess is the pickup tube o-ring or bypass relief valve or the pump und spring. Which fom my understanding all require the removal of the pan. I have a all-wheel drive and so it's going to be a pain to do for a bit and I'm not going to get to for a month or more.

What would you do for a short-term fix? Thicker oil like a Lucas oil stabilizer? I've also read that adding an extra quart or two of oil may temporarily put the o-ring under enough oil that it actually sucks, if that's the issue. I don't know much history on this car. I just purchased it.

I've read posts for about the last hour and I'm not finding a good all-in-one, while you're in there fix this also type of thread for dropping the oil pan. Does anybody have a good list?

Assuming it's going to be a month or two before I can get to it. What are the best short-term fixes?

Oil pressure when it's driving seems to be around 25-40. It mostly just drops really low when I'm sitting at a light. Oil pressure climbs basically about 10 psi for each 1000 rpm.

I also forgot to address your initial question of long-term vs short-term:

Oil is the life blood of your truck. Personally I wouldn't bandaid anything and would figure out HOW to make the time to fix it.

But, that being said, IF time isn't on your side, then a thicker oil will help some. I did that on my 2007 Denali with the same issues you stated. I ran 10w-30 synthetic blend. This did help the situation, but it was also summer when I did this to get by until I had all the stuff I needed.

 

[Dustin Jackson]

@weekendernutjob This sounds stupid but if you just got the truck I would give it an oil change and see what happens man

 

[WeekenderNutJob]

@weekendernutjob This sounds stupid but if you just got the truck I would give it an oil change and see what happens man

Yes, I did a oil change today and I also did a engine flush at the same time. I would say it helped the operating pressure when driving to be more like 30 or 40. But still the idle pressure when it's idling it like 700 RPM seems like the oil pressure is only like 5 PSI. This is concerning to me. Does anyone know what good operating pressure is if it's idling and warm?

 

[Blackcar]

Yes, I did a oil change today and I also did a engine flush at the same time. I would say it helped the operating pressure when driving to be more like 30 or 40. But still the idle pressure when it's idling it like 700 RPM seems like the oil pressure is only like 5 PSI. This is concerning to me. Does anyone know what good operating pressure is if it's idling and warm?

Seems like you would get oil pressure light on dash at that oil pressure?

 

[Fubar0715]

Honestly, consider dropping the pan and replacing the O-ring. This will also give you a chance to have a look for leaks underneath. In my case, I replaced oil pan gasket, cooler line block plate, and the O-ring on the pick up tube - dramatically changed my oil pressure and cleaned up the leaks strewn across the bottom of the engine...Was about 6 hours of work to get it all wrapped up - less than $50 in parts.

 

[B-train]

Yes, I did a oil change today and I also did a engine flush at the same time. I would say it helped the operating pressure when driving to be more like 30 or 40. But still the idle pressure when it's idling it like 700 RPM seems like the oil pressure is only like 5 PSI. This is concerning to me. Does anyone know what good operating pressure is if it's idling and warm?

My 2008 6.2L will run a minimum of 20 on the guage at idle. This moves a little depending on temp, but it never goes below that. My 2007 Denali would actually have lifter rattle on a warm restart before I did the oil pickup o-ring and top plate o-rings. That was hot summer temps though, so everything was HOT and thin. I learned as I went and that was the last straw that made me learn, dig, and repair.

 

[Foggy]

There is a "test" for the pump O ring issue...
Add 2 extra quarts of oil to the engine and idle it on a downhill grade.. not extreme though.
If you oil pressure is better, than it's prob the oil pump p/u tube O Ring...
But don't keep running the extra oil... that's a big NO NO
At least you'll know ... I don't really know it this is a 100% diagnosis but it's easy;cheap and
worth a shot...
The advice on the lifter valley O rings is also solid... they will puke oil pressure if not
sealing to the valley plate correctly.. It's pretty easy to do as well

 

[Dustin Jackson]

@weekendernutjob I don't know if this applies to the AWD model but I heard that you can remove the oil pan without dropping the front diff entirely