These "Acceptable Oil Consumption" Levels May Be Higher Than Your Comfort Level.
Window stickers may be quickly approaching $100k but there's something much more alarming that is climbing, and this isn't going to make you feel good, at all.
You thought DEF usage was bad
Don't even get me started on DEF usage, we all can agree that it's getting more and more costly to operate these 6.6L Duramax Diesel Engines while doing our part of "saving the environment". The latest concern is that of engine oil consumption. In a document from the National Highway Traffic Safety Administration (NHTSA), claiming 2.5 quarts of oil consumed within 1000 miles is acceptable. The document states this is normal due to the engines requirements for lubrication and when a piston moves down the cylinder, there is a thin film of oil left behind which in turn gets burned during the combustion process. To add to this, there is a direct relationship with how hard the engine is working. As in, if you are towing or under a lot of strain, the oil consumption can climb. Other factors contributing to this could be from: High Speed or High RPM driving, PTO Operation, a malfunctioning PCV system, Oil Dilution from Condensation (very short trips can do this), High Engine temperature or even just plain old engine wear.
It Wasn't Always That High
L5P (2017 to 2024) has an acceptable rate of 2.5 Quarts per 1000 miles
LMM / LML / LGH (2007.5 to 2016) has an acceptable rate of 1.25 Quarts per 1000 miles
LB7 / LLY / LBZ (2001 to 2007) has an acceptable rate of 1 Quart per 1000 miles
The L5P is in 2017 to 2023 2500/3500 Trucks with an updated L5P making it's way into 2024 model year. These are the years where 2.5 quarts of consumption is ok, but how about the prior years?
LMM / LML / LGH (2007.5 to 2016) has an acceptable rate of 1.25 Quarts per 1000 miles with "Heavy Towing" upping the allowable to 1.38 Quarts per 1000 miles.
LB7 / LLY / LBZ (2001 to 2007) has an acceptable rate of 1 Quart per 1000 miles but I was unable to find a spec that included "Heavy Towing" but you can see where I am going with this.
"Back in my day" if an engine was consuming oil, that meant it had an issue that needed to be looked into further and it likely was going to be a costly repair, potentially a new engine. Nowadays, it seems we are OK with burning oil, we have the giant soot catcher to collect it and burn it off, so who cares? I Do ! And you should too, so go check your oil level and more so when towing. Keep the shiny side up and rubber side down.