2021 Duramax L5P oil consumption cause and solution

Joined
Oct 5, 2020
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I have a 2017 Duramax L5P with a Banks Derringer that I run on level 6 all the time. I tow a 15k fifth wheel and sometimes have another trailer behind it depending on what I am wanting to do. My 17 has a smaller oil cooler than the OP 2020 and Gale Banks did a comparison of the two several years ago, and he actually offers a kit to upgrade the earlier L5P to the newer oil cooler. That being said, when working the engine hard with high EGT's the engine oil is squirted onto the bottom of the piston to help transfer piston heat to the oil. If oil temps gets much above 220 degrees you better back off because the oil is getting too hot and consumption can go up. I only run 5W40 in the winter when it gets very cold and I can't plug in the block heater because 15W40 offers more protection that 5W40 in most oils. That being said, head winds are a pain, fuel economy drops like a rock and EGT's get much higher because of the increased engine load. I two will drop gears to keep my EGT's in check. I typically drive with my instant fuel economy pulled up on my dash and I will pull the highest gear that gives me the best fuel economy. My engine has on occasion used a little oil, but probably because I worked the engine very hard and got the oil temp too hot. I run 5000 mile oil change intervals and use a good quality 15/40 most of the time. In the last year oil brands have been hard to pin down, but I usually have a years worth on the shelf.
 
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The land of USA-made Subies!
If you can somehow get your dealer to put you in touch with a zone rep I would pose the question to him/her and then ask for it to be kicked up the chain to current product engineering. You would probably need to vet whoever responds to make sure they arent just passing you off on some low level customer service functionary. Youre going to need to climb the food chain to get an actual answer from someone with the knowledge.
Anything less than that is anecdotal.

After using a scan gauge on my 2005 LLY D-max I found that the truck would often stay in 5th gear when it actually would have run more efficient with lower EGT's in 4th. After finding this info years ago I always felt the truck up-shifted quicker than I wanted when towing.
I spent some time talking with an really smart guy today about the “static momentum” of really large companies. They made their money and lost their competitive edge. The market is something millions watch on TV on Sundays, and one of the Big 3’s top engineers steered this customer to Mobil.

Long story short, there was no improvement. A call to the guy in question and a week of development, followed by a month of real-world testing showed they had a fix for something Mobil couldn’t/wouldn’t.

@wwillson you know who I’m talking about, he’d be my first contact for the “why” and the resolution.
 
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May 15, 2012
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The land of USA-made Subies!
Not sure what your post has to do with my comments. Its a little too cryptic for me to follow.
Sorry, got sidetracked. You had mentioned contacting GM, and my point there was that most of the people involved at the corporate levels are either bound by contract or “tribal knowledge” or ignorance, and will simply repeat an official line- like if you called Chrysler about oil for the Dodge Demon, they’re going to tell you 100% of the time to use the Pennzoil 0w40. There’s no outside the box thinking or real understanding in their answer; they aren’t the lubrication engineers nor even in the lubrication industry. They regurgitate what they’re told- but on the flipside, this board does have several contacts inside the lube industry itself and can take a specific application and good feedback to these people and get a much more appropriate lube… does that clear it up? 👍🏻
 
Joined
Jan 10, 2017
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Michigan
I understand now. Part of your point is why I originally mentioned vetting the people that someone is in contact with. Like any other organization, GM has many very dedicated folks that work very hard to resolve issues. (and probably a few duds too, thats the problem with hiring humans)

Thanks.
 
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