Is Your Gmt-900 Truck Or Suv Using Oil

GuyGene · August 14, 2014

Ok, I've been reading all I can about this issue, and it seems to me the combination of disabling AFM and using oil catch can when truck is still really new (1,000 miles or less) just might be the ticket! I really think old cow hit on it with his '13 by doing those two things right away.

HateCarpetGuy · August 15, 2014

Guy Gene,

FWIW: On my high mileage 2008 CC 4wd with 5.3, etc.: truck used to burn oil like they all seem to do. After reading up on the issue I went old school to confirm: I ran a compression check on all 8 cyl. (with AFM, I considered only checking 4, LOL). All cylinders were high and even, therefore rings were good. The topside was the culprit, I changed valve cover to get new PCV design and disabled AFM. No can was installed. ALL oil consumption stopped, like nearly zero. I do not have to add oil btwn changes, and its been like that for over 100K miles. I did not have to add "can", that seems to only treat the symptom, i.e. catch the oil vs stop the leak.

I have been very pleased with the 2nd life in the truck. She likes running on all 8 cylinders all the time, gas mileage has not changed, oil stays in crankcase, computer tweak got the govt out of the engine. She actually runs better today than 4.5 yrs ago when I got it with 99K.

Daily Driver - 353K

Cowpie · August 15, 2014

One thing for certain, I have never heard or read where anyone regretted disabling AFM. Virtually 100% positive comments when they do it. Mine was only AFM enabled for about the 1st 240 miles on the odometer. Been disabled ever since. I noticed an improvement right away. Smoother cruising and acceleration. Many claim a person can't really tell the difference, but I sure can.

GuyGene · August 17, 2014

Guy Gene,

FWIW: On my high mileage 2008 CC 4wd with 5.3, etc.: truck used to burn oil like they all seem to do. After reading up on the issue I went old school to confirm: I ran a compression check on all 8 cyl. (with AFM, I considered only checking 4, LOL). All cylinders were high and even, therefore rings were good. The topside was the culprit, I changed valve cover to get new PCV design and disabled AFM. No can was installed. ALL oil consumption stopped, like nearly zero. I do not have to add oil btwn changes, and its been like that for over 100K miles. I did not have to add "can", that seems to only treat the symptom, i.e. catch the oil vs stop the leak.

I have been very pleased with the 2nd life in the truck. She likes running on all 8 cylinders all the time, gas mileage has not changed, oil stays in crankcase, computer tweak got the govt out of the engine. She actually runs better today than 4.5 yrs ago when I got it with 99K.

Daily Driver - 353K

Now, that is the ticket indeed!! Just changed one valve cover? How ye disabled that AFM mess? I just wonder why in the world GM won't put the right kind of valve cover on trucks?!

I like cow's idea of doing whatever you do straight away. Stop the mess before it gets started!

midwestfisherman · September 20, 2014

I have a 2008 Silverado LS 2WD with a 4.3L V6. It uses about 1 qt of oil per month. I'm reading through this thread now to see how people have fixed this. I bought the truck used so I have no warranty on it.

arz71 · September 20, 2014

What is the part number for the valve cover and what tool did you use to disable the AFM?

I have a 2009 Silverado 1500 4x4 with the 5.3 iron block.

Can someone please post the how-to or info and part numbers?

thanks

Bad Bowtie2 · September 24, 2014

What is the part number for the valve cover and what tool did you use to disable the AFM?

I have a 2009 Silverado 1500 4x4 with the 5.3 iron block.

Can someone please post the how-to or info and part numbers?

thanks

The new left valve cover for the 2009-2011 AFM trucks is GM PN# 12642655.

There is a different PN# for the 2007-2008 trucks??

Alot of us are using "The Range" device to turn off AFM....

Edited September 24, 2014 by Bad Bowtie2

Farmingdales Finest · October 9, 2014

2007 5.3 Cast Iron with AFM. Around 50k miles. Average approximately 5000 between changes. Changed the oil around 40k miles, added one quart before the next change. The same thing happened after the next change. 1000 miles after my most recent change it needed a quart, added another quart today, after about a 1000 more miles. Information center says oil is currently at 55%. At this rate I'll use 3-4 quarts between changes, 10,000 miles ago it was zero. Taking it to the dealer as soon as I can.

This sounds like my 2007 Yukon xl. Excessive oil consumption started somewhere around 35-40,000 miles with about 1-1.5 qts every 3000 miles and now its at least a quart every 1000 miles. I now have 129,00l0 miles and had to have an engine flush last week after driving home it went from sounding perfect to a loud metalic banging that got louder as you accelerated. I had it towed to my mechanic and he sufggested the flush first and if that didn't work he expected lifter damage.

Edited October 9, 2014 by Farmingdales Finest

HateCarpetGuy · October 10, 2014

How to stop Oil Consumption:

1. Turn OFF AFM, this hair-brain system shuts down 4 cylinders for a virtually unnoticeable improvement in fuel mileage. This is to appease the EPA anti-oil folks that demand car companies achieve unrealistic standards. Turn off AFM and let your V8 run like a V8. Where do you think the saying "running on all cylinders" came from? I took mine to a speed shop that turned off AFM, when I asked the guy "so, what all did you do"? his response was "don't worry about the details - I just got the Govt out of your engine, it should run a long time now."

2. To be sure you don't have a piston - ring wear problem, do an old-fashioned compression check on all cylinders. This will let you sleep at night knowing that the bottom half of your engine is sound. Most problems are in the top half associated with AFM and the PCV valve built into the valve cover. (see above for part #)

3. Install the upgraded valve cover that has the new design that actually keeps oil where it should be and allows air back into the intake manifold, not oil. With the original design the oil blows out of the valve cover and accumulates in the valleys of the intake manifold. It then spills over into the engine as you ride, most noticeable at red lights on a hill.

I performed the above steps on my truck at 180,000 miles and it has run super ever since. It runs better today than it did 4 years ago when I got it at 99K. Oil change at 5K, Tranny fluid at 50K, all fluids, belt, spark plugs at 100k.

2008 CC 4wd 5.3 Daily Driver - 360,000 miles

MaverickZ71 · October 10, 2014

How to stop Oil Consumption:

1. Turn OFF AFM, this hair-brain system shuts down 4 cylinders for a virtually unnoticeable improvement in fuel mileage. This is to appease the EPA anti-oil folks that demand car companies achieve unrealistic standards. Turn off AFM and let your V8 run like a V8. Where do you think the saying "running on all cylinders" came from? I took mine to a speed shop that turned off AFM, when I asked the guy "so, what all did you do"? his response was "don't worry about the details - I just got the Govt out of your engine, it should run a long time now."

2. To be sure you don't have a piston - ring wear problem, do an old-fashioned compression check on all cylinders. This will let you sleep at night knowing that the bottom half of your engine is sound. Most problems are in the top half associated with AFM and the PCV valve built into the valve cover. (see above for part #)

3. Install the upgraded valve cover that has the new design that actually keeps oil where it should be and allows air back into the intake manifold, not oil. With the original design the oil blows out of the valve cover and accumulates in the valleys of the intake manifold. It then spills over into the engine as you ride, most noticeable at red lights on a hill.

I performed the above steps on my truck at 180,000 miles and it has run super ever since. It runs better today than it did 4 years ago when I got it at 99K. Oil change at 5K, Tranny fluid at 50K, all fluids, belt, spark plugs at 100k.

2008 CC 4wd 5.3 Daily Driver - 360,000 miles

HCG, did you install the 'deflector' inside the oil pan when you installed the revised valve cover?

j-ten-ner · October 11, 2014

...2008 CC 4wd 5.3 Daily Driver - 360,000 miles...

Thanks for giving back hope...that those engines are still capable of longevity.

so long

j-ten-ner

Cowpie · October 11, 2014

My 2013 had the newer valve cover, but I still used a catch can on the PCV line and catch about an ounce of oil every 1000 miles with it. The oil deflector "improvement" that GM made might stop larger amounts of oil from getting into the PCV line, but will do nothing for misted, small particulate oil that is carried along with the crankcase gasses up the PCV line. This is an issue no matter the engine size, brand, etc. Not just a GM issue.

Hulkster529 · October 24, 2014

2013 GMC Sierra 5.3. 28,000 miles. Got check engine light and rough idle. Took to dealer and it was 2.5 quarts low and #1 spark plug was fouled. Doing a oil consumption test now.

Cowpie · October 30, 2014

That's too bad that a 2013 should already be having issues. My 2013, with roughly the same number of miles, barely uses a drop. I have 5000 miles on this fill of engine oil and the level has barely moved off of full. Been pretty much like that since I bought it. But then, I attacked the problem issues within the first 1000 miles like disabling AFM and installing a PCV catch can. Thing is, I really hadn't kept up with this stuff until I bought this pickup. Right away I started reading various forums, saw what was going on, and immediately started preemptive measures before the engine had time to go goofy.

kaleb b · November 3, 2014

05 Silverado 5.3 Z71 extended cab, lifter noise on startup I use dealer oil, basic mobile 1 blend I believe and I have to put a quart in about every 1000 miles, no leaks that I can detect so I don't know where it goes...157k miles right now on an iron block with aluminum heads.

Edited November 3, 2014 by kaleb b