2007 GMC 5.3 AFM Using Oil?

[ccracin]

We have a 2007 GMC Sierra Crew Cab 4x4 with the 5.3 that has active fuel management. NOT flex fuel. We changed the oil about 2K miles ago and noticed that we only got 4 quarts out of it. The previous change was done by the dealer. We thought maybe someone made a mistake at the time. So will filled it to the full line on the dip stick. Almost 6 quarts. Then the day before yesterday my Dad started it in the morning and it made a terrible mechanical racket. He immediately looked at the oil pressure gauge and "0". As he went for the key to shut it off the needled jumped and the noise quit. He shut it off and checked the oil level. It was about an inch down on the stick. Probably 1.5-2 quarts low. We got it up on the jack and crawled around under it. No visible leaks and no drips on the driveway. It also does not smoke. WTF! Anyone else seen this? He took it to the dealer yesterday and they made him an appointment this morning. They are going to change the oil and have him come back in 1k miles to check the level. Can someone check to see if there are any bulletins on this? I want to be prepared to "discuss" this issue. Thanks for any help.

Later,

[LS1NOVA]

Gm engineering is looking into this exact problem right now. The current info says to check the under side of the valve covers for problems with the breather baffling. It then says to run the engine with the valve covers off and note any pushrods with excessive oil shooting from them. Lifters have fixed some of them. We have had a few with carboned up and stuck pistons rings. Your noise problem sounds like a DOD lifter problem and could cause the oil consumption problem too.

There is also an oil consumption bulletin for nicked valve stems and oil getting by the seals requiring head replacement.

If they want to put lifters in it or teardown and inspect the engine thats ok but they might just tell you they need to monitor the oil consumption and wait for GM to release their magic fix.

[ccracin]

Thanks Nate. Very much appreciated.

[XcYZ]

That's interesting, Nate. I have a 2007 L76 6.0 with AFM. I've noticed that it has used some oil, too, but not nearly as much as what Chad noted.

[ItDoRun]

I have the same truck (2007 GMC). I've noticed a slight knock when the engine is started but immediately goes away after about a second. I guess I better check the oil level in it when I get home. I have a 2008 silverado for a company truck that has the same knock in the mornings when I leave for work. I guess I better check that one too.

[jack67rs]

I would also pay attention the steering tie rod setup on those trucks too! One of our guys from work was driving his 2007 GMC and his steering developed a vibration and let go, sending his truck off road into a tree. One of the steering rods had seperated. Gm did'nt want to warranty it and now his insurance company is going after Gm. BTW, he did find a bulletin showing concerns of a possible problem. And yes, I have the same thing on my 2007Avalanche.

[Chris442]

There's been a little discussion about DOD lifters going south on one of the G8 boards here, but nothing too concrete on it. I'll have to keep my eye on the oil my Mom's G8.

I guess this is why G8 L76 holds 8.8 quarts of oil. It's one expensive oil change if use syn, though.

[LS1NOVA]

That cold start knock can also be piston slap due to the short skirts on Gen3 and 4 engines. Pretty normal to have that.

[Ummgawa]

Same Oil use on my 5.3. Still the best damn vehicle I have ever owned.

[ccracin]

We are doing the oil test they wanted to do now. I did find a tech bulletin that says 1 quart in 2000 miles is acceptable. That's BS. That is GM's way of skirting the problem. We'll see what happens. If anyone of us built an engine and it used a quart of oil in 2k miles, we would tear it back down. It's still a great truck, but will be gone at the end of the warranty.