High mileage engine oil.

[vtfireman85]

Long story short, we have a GM 6.0 that the oil pressure is dropping off, used to idle at 40 psi, now down to 30, it’s not an alarming number, but it is a change. Truck has 180k on it, and I just switched to 10-30 to see if it made a difference, it didn’t. What are the high mileage oils all about and are they worth trying? 

[yellowrosefarm]

31 minutes ago, vtfireman85 said:

Long story short, we have a GM 6.0 that the oil pressure is dropping off, used to idle at 40 psi, now down to 30, it’s not an alarming number, but it is a change. Truck has 180k on it, and I just switched to 10-30 to see if it made a difference, it didn’t. What are the high mileage oils all about and are they worth trying? 

They are pretty well known for the o ring on the oil pickup tube going bad and causing that. I had to do the one on my 01 Yukon 5.3 which fixed the exact situation you have.

[dale560]

Dexos oil in the high mileage helps. The oring is a problem but so is the oil pump. Beet thing is to pull the oil pan and timing cover. Swap out pump, pickup oring and relief valve in pan.

[vtfireman85]

21 minutes ago, yellowrosefarm said:

They are pretty well known for the o ring on the oil pickup tube going bad and causing that. I had to do the one on my 01 Yukon 5.3 which fixed the exact situation you have.

On the oil pump I assume you mean? 

[vtfireman85]

2 minutes ago, dale560 said:

Dexos oil in the high mileage helps. The oring is a problem but so is the oil pump. Beet thing is to pull the oil pan and timing cover. Swap out pump, pickup oring and relief valve in pan.

Having not had one of these very far apart, why am I pulling the timing cover? Should I be doing a new timing chain while I am in there? 

[dale560]

2 minutes ago, vtfireman85 said:

Having not had one of these very far apart, why am I pulling the timing cover? Should I be doing a new timing chain while I am in there? 

+oil pump is front of crankshaft. You can swap the pump carefully just through timing cover. But you really need to pull pan and do it right. Clean or replace pickup tube, relief valve in pan , oil pump, chain and guides. I am just in process of going to do this on my 13 with 5.3 amf and vvt. It’s not bad to get pan off . You probably need some parts in the 4wd any way. If 4wd pull diff, drop bolts out of steering rack. And I think exhaust can stay. You just can clean everything up good and run it a long time again. After I am done with 5.3 I have to fix wife and kids 6.0 in a hand me down 2500. I usually pull valve covers and clean pcv tunnel also just to get everything ship shape. Rock Auto. Is your friend here. Look for a good melling high volume pump not high pressure but high volume. Have done a couple of these already. Got 287000 miles on the 13  5.3 I am going to do here in a bit.

[vtfireman85]

@dale560, Being a van It still seems like a no fun kind of job. Thanks for the advice as always. 

[Jacka]

1 minute ago, vtfireman85 said:

@dale560, Being a van It still seems like a no fun kind of job. Thanks for the advice as always. 

I don't know about you but the older you get nothing to me fixing or mechanical is a "fun kind of job". Its just some are less hateful than others.

[yellowrosefarm]

I just pulled the pan and replaced the o ring on the pickup tube. Mine is 4x4 but I did not have to pull the center section or exhaust. On a 2wd van it shouldn't be that hard, I wouldn't think. It's been 8 or so years ago and the oil pressure has been fine since.

 

[Lars (midessa)]

Confirm the the oil pressure gauge, and sending unit is accurate. Also check the output of the alternator at idle, a weak alternator ‘can’ mess with electronic gauges.

[vtfireman85]

26 minutes ago, yellowrosefarm said:

I just pulled the pan and replaced the o ring on the pickup tube. Mine is 4x4 but I did not have to pull the center section or exhaust. On a 2wd van it shouldn't be that hard, I wouldn't think. It's been 8 or so years ago and the oil pressure has been fine since.

 

4x4 van, so who knows. 

[vtfireman85]

1 hour ago, Jacka said:

I don't know about you but the older you get nothing to me fixing or mechanical is a "fun kind of job". Its just some are less hateful than others.

My issue is that without the truck I am not getting much done, whenever I try to work on anything I get interrupted, finding a component mechanic to do anything very involved is next to impossible, so I end up either frustrated at a halfass job or I end up doing it myself. If I could be left alone I might actually enjoy it. 

[Rawleigh99]

Valvoline Restore and Protect is some top notch oil that will clean out all of the deposits without clogging the oil filter.   Is it burning oil like a stuck ring?  if so, this is what i would go for.  If not burning it, it may be the o ring.  Either way, go with Valvoline Restore and Protect.  

Look up Lake Speed's Youtube videos on it, complete with dyno testing and oil analysis.  He is a real oil scientist with a degree and this is what he does for a living, so it is not just another opinion.

[Jacka]

1 hour ago, vtfireman85 said:

My issue is that without the truck I am not getting much done, whenever I try to work on anything I get interrupted, finding a component mechanic to do anything very involved is next to impossible, so I end up either frustrated at a halfass job or I end up doing it myself. If I could be left alone I might actually enjoy it. 

I understand.I due as much as I can myself for your exact reasons.I fortunately can and I  am left alone. Nothing is better then working your own pace,fixing your own screw ups without someone breathing down your neck.I work at something,quit when I want,work as long as I want.I just get tired quicker I think.I just hate working on cars or trucks. My limit any more IF it is easy is exhaust, radiators, waterpumps,alternators'oil changes.I however don't do one thing on my wife's SUV.Oil changes,through brakes, waterpumps and transmission all done by 3 different very trustworthy mechanics.

I do however get satisfaction from working on my farm machinery, tractors,skidloaders,bulldozer and backhoe.Something about making something better and figuring out what was wrong is satisfying. 

[yellowrosefarm]

I loosened the motor mounts and raised the engine as far as I could to get the clearance. If it's a Quigley van, you may have enough lift already. It just needs to come down enough to get your arm in there with a socket to loosen the pickup tube and take it out with the pan.  Others may have another way.

[Chester5732]

30 psi at 180k?  I wish mine was that high. I just run it and change the 5w30 every 3000. 

[yellowrosefarm]

Going back, I used a couple of small zip ties to hold the pan gasket in place, started a couple of bolts, then cut the ties and pulled out.

[yellowrosefarm]

Just now, Chester5732 said:

30 psi at 180k?  I wish mine was that high. I just run it and change the 5w30 every 3000. 

Mine is 45 still at 215,000. Was 30 before doing the o ring all those years ago.

[dale560]

2 minutes ago, Chester5732 said:

30 psi at 180k?  I wish mine was that high. I just run it and change the 5w30 every 3000. 

They will drop to 20 psi at speed when bad. It doesn’t hurt anything other than oil warning light comes on. 

[dale560]

1 hour ago, vtfireman85 said:

My issue is that without the truck I am not getting much done, whenever I try to work on anything I get interrupted, finding a component mechanic to do anything very involved is next to impossible, so I end up either frustrated at a halfass job or I end up doing it myself. If I could be left alone I might actually enjoy it. 
 

dropping the diff out is t that bad of job a couple hours. But with a van could be more. And the timing cover on pickups isn’t bad once you get pulley off crank and water pump off.  If you are going through the work I would definitely get the pan out off there and clean it. I am not sure on the non afm engines but I think they all run the relief valve in oil pan that is another known leak point. Again do it right and take 10 hours or so vs the 5 for just pulling pan. It would actually be easiest to do timing cover and oil pump plus oring if you don’t want to mess with pan. But again I can’t stress enough how important it is to clean up everything including sump and pan.

[dale560]

Looked it up and some 6.0 liters don’t use the second relief valve in pan. If you look at the video posted that sludge is in the pan always.

[acem]

16 hours ago, vtfireman85 said:

4x4 van, so who knows. 

4x4 van? 

We need pics!

 

[Chester5732]

10 minutes ago, acem said:

4x4 van? 

We need pics!

 

 

It looks like a 2wd. GM sold them as an H body instead of the G body for a full size van. 

[vtfireman85]

1 hour ago, acem said:

4x4 van? 

We need pics!

 

 

 

1 hour ago, acem said:

4x4 van? 

We need pics!

 

 

This one isn’t very exciting to look at, you might not notice, 2500, the 4wd components cross to a 2004 2500hd pickup, the van components are the same. The last one was cool looking, leaf springs and a Dana 44, which was undersized. 

[TN Hillbilly]

On 8/5/2026 at 5:58 PM, yellowrosefarm said:

Going back, I used a couple of small zip ties to hold the pan gasket in place, started a couple of bolts, then cut the ties and pulled out.

That is a trick I need to remember!