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Discussion Starter · #1 ·
I am curious, I see the AFM blamed for oil consumption. Granted it has flaws poor design etc. But, how does this cause oil consumption? Is this just what is accepted or it there an explanation of the AFM causing this problem. The AFM process will definitely suffer from oil consumption and I would not want AFM on if I had a consumption issue.

Cause and effect what is going on here? Am I missing something?
 

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Discussion Starter · #4 ·
According to this... Valve spray causing deposits. Granted it may be redirected etc but at the same time the deposits are from contaminants in the oil. Still related to amount of carbon in the oil. Whether change interval oil quality detergents etc.

I do see the relation as in the valve and I agree that its not designed well nor is the AFM. In fact the basic flaws of the internal combustion engine are completely overlooked or ignored. Where can you stop? I will say the direct injection system is somewhat in the right direction but a little side stepping the problem.

A better filter may even help. I am all for longer intervals if you can keep the engine and oil clean without deposits but that is the very point I'm making.
Question is are the deposit much worse as I suspect with dirty oil?
Maybe its is maybe its not, hopefully we will find out. What I've done with mine has worked and only got better. Although, I haven't had an issue with the rings either.

Here is another question? Is the valve non functional when disabling the AFM?
 

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Well, for what it is worth, my truck started using a ton of oil (2 quarts in 3k), I disabled AFM 500 miles later with an inTune, so all the hardware is still there just the system never activates. I just recently changed my oil again, 8500 miles, used 1/2 quart or less during that time.

Now, to be fair, when I first got the truck, it didn't use anything worth mentioning during that change the dealer had put in it, for about 6k miles. I don't know what oil they used, but I started using Mobil 1 like I have used in my vehicles for years. Did that trigger something? Maybe, seems unlikely since the oil usage practically stopped after I tuned out AFM.
 

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Discussion Starter · #7 ·
If we are just talking about loosing pressure to the valve malfunction then we either have a faulty valve or buildup in the valve causing the problem.
If lifter failure...
Yet again, look at the design of the hydraulic lifter. Open one up and look inside. What is failure of the lifter? It cannot pump up or hold pressure. It is a catch can for contaminants in the oil. This is actually a wear issue with dirty oil as you have so much carbon settling inside the lifter. Where else can the AFM cause the lifter not to hold pressure?

Seems the valve is not designed to work with dirty oil. I see your point but It still seem must less trouble just to keep the oil cleaner. What other issues... blockages will show up?
 

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The afm cylinder lifters are different than the others. Thus why they make a DOD kit which gets ride of them and the other mechanical components in your engine eliminating the whole system.. Again google is your friend, this topic has been covered many times in the almost 10 years the system has been out.
 

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Discussion Starter · #9 ·
SparkyJJO said:
Well, for what it is worth, my truck started using a ton of oil (2 quarts in 3k), I disabled AFM 500 miles later with an inTune, so all the hardware is still there just the system never activates. I just recently changed my oil again, 8500 miles, used 1/2 quart or less during that time.

Now, to be fair, when I first got the truck, it didn't use anything worth mentioning during that change the dealer had put in it, for about 6k miles. I don't know what oil they used, but I started using Mobil 1 like I have used in my vehicles for years. Did that trigger something? Maybe, seems unlikely since the oil usage practically stopped after I tuned out AFM.
Isn't supposed to be changed after the first 1500 or so miles to remove the additives to break in the engine? I wondered if the added way to much to mine. It had settlings in the oil pan and clumps at 27k. It may have not ever been changed. Ill have to kick myself for that one. First vehicle that I didn't really check the engine on. It was a CPO and warrantied and virtually new and I trusted that. Turns out its just a bunch of BS. LOL 9 times out of 10 if they can get away with it they will. Case in point look at the issue were talking about! :lol: If it had seriously been checked out, the oil would be changed... inspected filters etc.

But even after that.. Ive cleaned it out fixed the problems still running strong. We will see after 200k maybe.
 

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Not all AFM systems have issues. With 125K miles on my stock 2009 Sierra, I'm only losing about 1/2 quart of oil every 5-6000 miles. Of course I've always used Mobil-1 oil and filter exclusively.
 

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I'm sure that thousands upon thousands of trucks with AFM don't have issues. That being said thousands upon thousands do. I am not willing to take that chance. Mines disabled and I am happy with that.
 

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AzDragonLord said:
Not all AFM systems have issues. With 125K miles on my stock 2009 Sierra, I'm only losing about 1/2 quart of oil every 5-6000 miles. Of course I've always used Mobil-1 oil and filter exclusively.
Careful man, I said the same thing about mine, until about 136k or so was when I noticed it drank the 2 quarts.
 

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There is much more to the equation than the advent of the AFM system. This problem seems to sneak up on the LS family of engines and yes it will almost always happen in the AFM engines before the non AFM. This has long been blamed on TOP TIER fuel or rather the lack of use of such fuel. The root cause has never been the fuel but rather the other gasses allowed to be consumed by the engine without filtering. This is becoming even more obvious in the LT engine family. GM just yesterday released a bulletin about some of the 2014 model year engines. Oil consumption is a byproduct of the problem. Draw your own conclusion. All I have to say is if you own a 2014 or newer truck, why does bank 2 always have a lower LT fuel trim than bank one?
 

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Gozzie said:
I'm sure that thousands upon thousands of trucks with AFM don't have issues. That being said thousands upon thousands do. I am not willing to take that chance. Mines disabled and I am happy with that.
Same here. Bought my one owner truck with 62,000 miles and used zero oil. Read about the AFM nightmares so I started out with a Range before any serious issues, then moved up to a tuner. Could not be happier with the results.

ferraiolo1 said:
^yep. That $350 tuner is safe insurance.

Sent from my iPhone using Tapatalk
Most definitely. A tuner is worth every penny.

apcnc said:
Anyone develop the problem with AFM disabled?
Not one problem. In fact I have seen better performance without the motor jumping between V8 and V4 mode.
 

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I have also been convinced somewhat, that taking the drain intervals to the max OLM and such are also contributing to the problem. While the oil may still technically be "good" by a lab report, that doesn't mean it actually still should be run. There is a build up of wear metals, contaminates, acids, etc that can have a detrimental effect on the AFM valves. While oil additives help mitigate the effects, things compound anyway. One of the reasons I decided to stay with no more than 5000 mile OCI's when I had my 1500 5.3L with AFM. I turned it off early on in the game, kept OCI's at 5000 miles, and I never used more than about 1/8 to 1/4 quart of oil over an oil change interval. Found out when I put on an oil catch can, where that oil it was using was going. Factoring out what the catch can captured over an oil change interval, my engine only was "using" maybe 1-2 oz of oil over that time. Pretty good.

For those already into the oil consumption game with their engine, I recommend a couple of times doing engine flushes with something like Amsoil Engine Flush. If one has the motivation, also removing plugs and doing a piston soak using AC Delco X66-P. That is some good stuff that can loosen up oil buildup on top rings. You have to do an immediate oil change. You put it in the cylinders and let it sit for several hours, then turn over engine (without plugs) to get the residual out and then change oil and reinstall plugs.
 

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Gozzie said:
I'm sure that thousands upon thousands of trucks with AFM don't have issues. That being said thousands upon thousands do. I am not willing to take that chance. Mines disabled and I am happy with that.
Folks on the internet saying they have issues with AFM does not make it true. I would suspect a very very small percentage for the folks accusing AFM have any real issue or even know what they are talking about. Folks in the USA will whine about anything, never bothering to get facts.
 
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