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LS 5.3 DOD AFM oil consumption

pajamasam

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Apr 12, 2011
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O'Hare Area
I'm have been having some oil consumption problems with my girlfriends saab 9-7x which is basically a tbss with a 5.3 instead of 6.0. It does have that displacement on demand or active fuel management which I think is the culprit. It's burning at least 2 qts per oil change.

I have been doing some reading and a ton of trailblazer, saab, and other 5.3 guys are having the same issue.

Some say replace drivers side valve cover with Pcv. Some say it's the AFM valve in the oil pan spraying on the pistons and rings. Some say tune out the AFM completely.

I am very good with LS motors and I don't mind ripping the heads off to put ls7 lifters in if I have too but I want to see what other people are doing first.

Thoughts?
 

pajamasam

Addict
Apr 12, 2011
725
2
O'Hare Area
Yea I'm almost positive it is. Because I have had two suburbans with 300k and 130k never burned a drop of oil.

The saab is an 2007.

I will check the blow by but I highly doubt it.

Also with the oil it burns I would think it would be fouling plugs left and right.


I was thinking about the catch can also just for something to try.
 

1quick

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I bought a can of the spray sea foam and soaked the pistons through the spark plug hole let it sit over night and that helped slightly but it still burns oil, I think if you did that a few times a year it may clear it up pretty good but I don't care enough about the issue to do that lol it's easier to just add a couple quarts
 

1quick

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I talked to a friend that works at a gm dealer he said there procedure was to spray gm top end cleaner into the cylinders and soak like that, he said the rings get coked up with oil and stick together causing bad blow by I can't confirm wether that's true or not but the piston soak seemed to help some like I said
 

Gone_2022

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Sep 4, 2013
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Not to bear bad news or burst a bubble but I believe on these engines GM has a very high tolerance for oil consumption. I believe there is a tsb bulletin that was close to 1.5-2 quarts per 3k or something like that. If I have some Time I will look it up when I get back to my desk. Honestly on an LS style engine if I hear of oil consumption I already know it's normal lol
 

Stink Star

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Jan 20, 2008
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I talked to a friend that works at a gm dealer he said there procedure was to spray gm top end cleaner into the cylinders and soak like that, he said the rings get coked up with oil and stick together causing bad blow by I can't confirm wether that's true or not but the piston soak seemed to help some like I said

This is what we used to do to free stuck rings, now we just replace the pistons.

Not to bear bad news or burst a bubble but I believe on these engines GM has a very high tolerance for oil consumption. I believe there is a tsb bulletin that was close to 1.5-2 quarts per 3k or something like that. If I have some Time I will look it up when I get back to my desk. Honestly on an LS style engine if I hear of oil consumption I already know it's normal lol

The "acceptable" consumption is 1/2qt per 1000 miles. Too high in my opinion but that's what will get you warranty work at a dealer.

Personally we haven't seen too many trailblazers but I've done about a million valve cover/ AFM deflectors and collapsed AFM lifters in c/k trucks. Usually cylinder 7 spark plug gets fouled out with oil and the thing misfires. It's tough to say what your issue is. I've fixed motors with the valve cover and deflector, and I've had to do pistons in some. Problem is, taking off the oil pan on a Saab 97x is pure hell. I'd just deal with it for now and get rid of the car ASAP..... It's that terrible to fix it
 

Gone_2022

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Sep 4, 2013
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This is what we used to do to free stuck rings, now we just replace the pistons.







The "acceptable" consumption is 1/2qt per 1000 miles. Too high in my opinion but that's what will get you warranty work at a dealer.



Personally we haven't seen too many trailblazers but I've done about a million valve cover/ AFM deflectors and collapsed AFM lifters in c/k trucks. Usually cylinder 7 spark plug gets fouled out with oil and the thing misfires. It's tough to say what your issue is. I've fixed motors with the valve cover and deflector, and I've had to do pistons in some. Problem is, taking off the oil pan on a Saab 97x is pure hell. I'd just deal with it for now and get rid of the car ASAP..... It's that terrible to fix it


I couldn't remember what it was but I remember it was one of the highest consumption I'd seen as acceptable. U beat me to it.

I second what you say. If at all possible I would sell the vehicle if your able to
 

bikrboy128

Some say.....
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Jul 15, 2007
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Personally we haven't seen too many trailblazers but I've done about a million valve cover/ AFM deflectors and collapsed AFM lifters in c/k trucks. Usually cylinder 7 spark plug gets fouled out with oil and the thing misfires. It's tough to say what your issue is. I've fixed motors with the valve cover and deflector, and I've had to do pistons in some. Problem is, taking off the oil pan on a Saab 97x is pure hell. I'd just deal with it for now and get rid of the car ASAP..... It's that terrible to fix it


i thought i read in a tsb about an updated deflector, but i wasnt sure if it actually worked.

it's probably pistons, so i would just deal with adding a bit of oil every so often :gives:
 
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