Oil Usage of the 5.3L / AFM

diyer2 · December 31, 2015

This is my two cents on this matter, I’m not disputing the excessive oil consumption some have experienced. I disagree with some of the procedures and maintenance intervals.

A GM owner for 46 years. Recently bought a 2012 Sierra, SLT, All Terrain, Ext. Cab, 5.3L AFM, with 42k miles and did not know of the oil consumption issue before purchasing. Found out about this issue on the internet.

I read a lot of posts about the high oil consumption issue after doing a search and posts on this forum. There are thousands of these motors without oil issues but I can sympathize with the unlucky ones who have had problems. If the problem was wide spread the line at the dealers would be blocks long given the number of vehicles with AFM.

I have been around motors of all types for years, gas, and diesels, including farming equipment, diesels in semi rigs, construction heavy equipment and fleet vehicles. Lawn equipment, outboards (4 stroke, 2 stroke), generators, motorcycles etc.

Helped build and built a few racing motors back in the muscle car era.

The frequency of oil changes is a personal decision that can be influenced by many factors. Nothing is perfect but I believe if you don’t abuse it and do the maintenance it will last.

I think of oil as a lubricant and a contaminant or combustion by product remover also. A sponge can hold a limited amount of liquid, oil can retain a limited amount of combustion by product, after saturation where does the combustion by product go?

Motors can use oil, some more than others. My 93, Silverado, 2WD, 5.7L, TBI with 243k miles uses a half quart every 3k miles between oil changes, sometimes more if I tow with it. With the high miles I use 20W50 in summer, 10W30 in winter.

The wife’s car is a 2007 Accord V6, with 83k miles and it uses zero to one fourth of a quart between oil changes at 3k mile intervals.

I experienced identical equipment using oil in different quantities, a motors assembly process is not perfect.

All motors have an oil dip stick, if it wasn’t necessary the manufacturer would not incur the cost of including one. If you wait until the low oil light comes on its too late IMO.

Every motor manufacturer recommends checking the oil level at regular intervals. My Sierra manual says “it’s a good idea to check the oil level at each fuel fill”, might be over kill but using a dip stick makes sense to me. A simple device that has no mechanical short comings, doesn’t need power, programing or sensors and its reliable.

I have always used conventional motor oil until know being this new truck requires semi-synthetic Dexos 1 certified oil. I figured why pay more money for oil and then throw it away, a personal decision. I also use fleet oil filters, the same thing they use at a fast lube business. I used Fram filters for years but switched to save a few bucks. You can buy fleet oil filters at auto parts stores but you have to ask for them and buy a dozen at a time to get the best deal.

Most products we purchase are mass produced and quality suffers sometimes, all we can do is try our best to minimize the bad purchases.

Will I switch to another brand of vehicle due to this issue? Why? Another brand will have a new set of problems if you happen to get a bad one.

I’m hoping my truck does not have an oil issue and I will update this in the future.

newdude · December 31, 2015

I had a 2012 1500 Silverado 5.3. In the 43k miles I had it, it never lost, if any, a 1/4 quart of oil? AFM was never turned off either. Truck was 100% stock. Oil was changed every 3k with Dexos certified synthetic blend and AC Delco filters.

If you have receipts showing your use of conventional, and you need warranty engine repairs and they ask for receipts, and they indicate you are not using a Dexos equivalent oil you do put your self at risk of voiding your powertrain warranty.

diyer2 · December 31, 2015

I will use Dexos,oil, I have that in my post, I think you miss understood.

I appreciate your input on your 2012.

I plan on driving this truck until they bury me so time will tell on oil consumption.

Bad Bowtie2 · December 31, 2015

I bought my 2009 & 2012 GMC Sierra's both new & changed the same oil & filter at the same time.

My 2009 5.3l never used a drop at 36K. My 2012 started using oil (20k) & it became progressively worse. GM pulled the 5.3l & rebuilt it (rings pistons, bearings) at 37K!! NUTS!!

With the precision accuracy & finite tolerances on these new LS engines, I really think it comes down to the guy installing pistons into the blocks all day. I'm gambling that it comes down to a few of these assembled engines having the piston ring gaps in the AFM cylinders being aligned too close. Were as, causing the blow-by/oil loss. These AFM cylinders become huge vacuum pumps when traveling down the highway, pushing & sucking oil past the rings. Just my opinion though. I'm not a GM engineer...

I bought my 2009 & 2012 GMC Sierra's both new & changed the same oil & filter at the same time.

My 2009 5.3l never used a drop at 36K. My 2012 started using oil (20k) & it became progressively worse. GM pulled the 5.3l & rebuilt it (rings pistons, bearings) at 37K!! NUTS!!

With the precision accuracy & finite tolerances on these new LS engines, I really think it comes down to the guy installing pistons into the blocks all day. I'm gambling that it comes down to a few of these assembled engines having the piston ring gaps in the AFM cylinders being aligned too close. Were as, causing the blow-by/oil loss. These AFM cylinders become huge vacuum pumps when traveling down the highway, pushing & sucking oil past the rings. Just my opinion though. I'm not a GM engineer...

diyer2 · January 1, 2016

Thanks Bowtie2,

Sorry to hear you got one of the bad engines. I agree its some problem in motor assembly that they haven't figured out or are not telling anyone.

No problems since the rebuild, how many miles now?

I have put about 1500 miles on my truck since purchasing it, city, freeway and mountain driving. Pulling grades, stop and go, and sustained high speed. I have used it in manual and drive with the AFM working. No oil use so far.

Nanotech Environmental · January 2, 2016

I'd suggest it's not an issue with assembly, but rather the parts that were spec'd for the design and operation parameters of the engines. The poor guys putting them together don't spec the parts, nor mess with them, as much of the process is automated.

The valve cover tray fix seems to work on many of the units.

The ones that GM had to rebuild likely had other issues, such as tolerance problems etc.

diyer2 · January 3, 2016

3beejay3,

Could be, we will never know the truth probably.

Sirstud1 · January 3, 2016

My 08 burns it also.. Sucks

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SilverSulley · January 8, 2016

A few months back my mechanic and I were talking about conventional vs. synthetic oils because I run rotella t in my chevelle during the summer. An interesting idea came about to keep track of how much oil I burn when I run conventional vs synthetic. My truck has 150k and It is well out of warranty, plus I'm planning a rebuild once I hit that 200k mark. Anyway, turns out I burn(or lose depending on how you look at it) through synthethic oil a hell of a lot quicker than conventional. Almost 2 to 1. I know it's a small sample size but I can't explain why. Thoughts?

diyer2 · January 9, 2016

My thought would be if you get down to the molecular level that the syn has smaller molecules. That is an interesting comparison.

Z45 · January 9, 2016

The word Synthetic is confusing; it describes a process, not a material. For example, white sand is synthesized into glass, but glass is never called "synthetic sand". Not all synthetics are created equal, so buyer beware. The cheap synthetics on the market may have very little Group III base oil in them since there is no regulation or oversight from the API on what is in the bottle. The work 'synthetic" commands a much higher selling price so it will get pit on the label at every importunity.

Supa711 · January 10, 2016

I bought an 08 5.3 a few months ago. First 5 thousand miles went through 2 quarts. Bought a range afm shutoff device and now 3 thousand later no consumption. I'm about to change the oil again to switch to full synthetic. I used a whole bottle of lucas feul treatment during this 3 thousand interval. And my oil is black. Hopefully I have cleared the carbon out.

Supa711 · January 10, 2016

If u don't use ur dipstick it'll get rusty. I couldn't resist anymore.

flyboyron · January 10, 2016

My truck, currently with 59,000 miles on the 5.3 doesn't use oil between oil changes. Maybe 1/4 - 1/2 quart, but that is it. I check it when I think of it, once or twice a year.

I have the dealer change the oil, so whatever they use is what's in there.

I run the engine until the DIC says 10% or lower which is about 7 - 8,000 miles before changing the oil.

So far no problems with the engine.

SidFarcus · January 11, 2016

I just checked and I am at 50% oil left on change and the oil on the dispstick is sitting at the lowest hole. Planning on turning off AFM by some device because I don't like how it feels going from V8 to V4.