JL Sargent Posted December 24, 2012 Share Posted December 24, 2012 I have an '07 GMC Sierra truck with the 5.3L AFM engine. My engine has 70K miles on it and I'm affraid of the oil consumption problems so many people have experienced with this technology. I know that the AFM can be turned off with a tune like Diablosport's intune or similar device. Anybody know about this? Quote Link to comment Share on other sites More sharing options...
MechMan Posted December 24, 2012 Share Posted December 24, 2012 If your not having a problem with it now dont worry. Use Dexos approved high milage oil and stay on top of your oil change intervals. Forget about Diablo...Enjoy your truck. Merry Christmas Quote Link to comment Share on other sites More sharing options...
JJkizak Posted December 25, 2012 Share Posted December 25, 2012 Not being privy to the latest advancements why would the oil consumption be affected with this AFM? JJK Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted December 25, 2012 Author Share Posted December 25, 2012 These engines have two modes of operation, V8 and V4. The problem seems to occur in V4 mode: Oil getting splashed up on the cylinder walls is carbonizing in the rings. The rings get stuck in their grooves. Oil flows past them. Defeating the AFM and the V4 mode seems to be the best "fix" for the problem. It's all over the net how this is occuring in these AFM engines. Those engines that predate the AFM technology do not have the problem. Mechman, I'm using Mobile1 high mileage which is DEXOS approved. I just want to avoid rings/pistons. You think I'm being over cautious? Quote Link to comment Share on other sites More sharing options...
MechMan Posted December 25, 2012 Share Posted December 25, 2012 I would not waste my money on Mobile 1. From what I have read and seen directly if you are at 70k miles you should not have a problem. I think it would have shown itself already. Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted December 25, 2012 Author Share Posted December 25, 2012 Any of those dexos are expensive. Which one do you recommend? Quote Link to comment Share on other sites More sharing options...
MechMan Posted December 25, 2012 Share Posted December 25, 2012 I personally use Quaker state Defy high milage in my truck. Just need to find out if that one is Dexos approved. my 99 is at 300k km but does not have AFM. Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted December 25, 2012 Author Share Posted December 25, 2012 I do know that Quaker State makes a Dexos certified oil I just don't know which one it is. I do know it has to be "full synthetic" for sure. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted December 25, 2012 Share Posted December 25, 2012 Jeff, the Dexos you get at the GM dealerships is not full synthetic. Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted December 25, 2012 Author Share Posted December 25, 2012 Hey Carl, what are your thoughts on turning off the AFM? Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted December 25, 2012 Share Posted December 25, 2012 As long as you're out of your emmission warranty (normally 80k miles) I don't see what it would hurt other than your gas mileage. If you have stuck rings and oil consumption issues because of stuck rings, theres a way to unstick them without pulling the motor down (Auto-rx). Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted December 25, 2012 Share Posted December 25, 2012 These engines have two modes of operation, V8 and V4. The problem seems to occur in V4 mode: Oil getting splashed up on the cylinder walls is carbonizing in the rings. The rings get stuck in their grooves. Oil flows past them. Defeating the AFM and the V4 mode seems to be the best "fix" for the problem. It's all over the net how this is occuring in these AFM engines. Those engines that predate the AFM technology do not have the problem. Mechman, I'm using Mobile1 high mileage which is DEXOS approved. I just want to avoid rings/pistons. You think I'm being over cautious? It only goes into v4 mode when you are idling or when you drive at a constant speed say highway, so you can technically defeat it if you play around with the gas pedal. As with the eco mode I am sure you can probably ask the dealership to flash it or get one of those flash updaters. Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted December 25, 2012 Author Share Posted December 25, 2012 I may be mistaken, but I don't think a dealership will turn this feature off for you. On the fuel economy: My wife drives the 2005 Tahoe with 5.3L non AFM that gets 16.2 mpg per the computer. It has 150K miles on it. This 2007 truck w 5.3L AFM motor averages 15.1 mpg per computer. So I'm wondering if mileage will really suffer at all? It would be nice to just run the Dexos oil and forget about the rest as Mechman suggests I just have a hard time trusting it with all the reports of high oil consumption on the net and the only fix being pistons/rings. Carl, you mentioned a flush for the stuck rings. I bet that is one strong chemical if it can really do it. Love the truck and I just want to protect my investment. Thanks for the sugggestions guys. Quote Link to comment Share on other sites More sharing options...
CECAA850 Posted December 25, 2012 Share Posted December 25, 2012 I may be mistaken, but I don't think a dealership will turn this feature off for you. It's not a selectable feature. If the vehicle was CARB certified with the feature engaged, the dealer can't turn it off. Carl, you mentioned a flush for the stuck rings. I bet that is one strong chemical if it can really do it. It's not actually a flush per se. You put the cleaner in and run it for about a thousand miles. It actually works. If your using oil because your rings are gummed up, your consumption will drop drastically. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted December 25, 2012 Share Posted December 25, 2012 http://www.diablosport.com/index.php/product-search Quote Link to comment Share on other sites More sharing options...
JL Sargent Posted December 26, 2012 Author Share Posted December 26, 2012 Yeah, those guys make a tuner called an "intune" that will do it. Interesting technology. Quote Link to comment Share on other sites More sharing options...
Jay481985 Posted December 26, 2012 Share Posted December 26, 2012 Basically someone mapped the ecu and with that device you can turn it on or off. My friend's audi has the same thing where you actualy need it to turn the check oil light when you do change the motor oil. You can turn off seatbelt warning lights, enable some other cool things as well. Quote Link to comment Share on other sites More sharing options...
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