Duramax 3.0L oil consumption while driving with low RPMs and high power output

[dbphillips]

New info: We are about 1000 miles into our summer trailer trip and the exhaust sensor failed. This was a couple days after getting a P0402 EGR code. And coincidentally a few days after seeing EGT of about 1200F for a short time climbing a minor hill in what appeared to be a reasonable gear. I backed off a little and got temperatures back down to around 1000. Otherwise, tow mode seems to select a reasonable gear and EGT stays below 1000.

Pray for us to get the backordered sensor in less than a month... I can get aftermarket right now, but I don't dare walk away from the warranty.

 

[smokey_2020]

Guys, need another opinion(s), I was so excited when I got my 2023 Duramax in May 2023, great vehicle with good mileage but it was a fest until I noticed that truck burns oil, 3/4 QT per 2500 miles. Second oil change of ACDelco 0w20 DexosD oil with OEM filter and it keeps burning. I am not seeing oil leaks anywhere.
Since GM released a TSB saying that 1QT per 1000 miles is normal for Duramax 3.0, dealer are not doing a thing about it. It leaves me with a question, I assume that rings are the problem and if I am to run approved Dexos D oils, I will just keep burning and need to carry 2 QT of oil on the long cross country trips? Switching to 5w30 will not address a thing?

 

[CleverUserName]

Guys, need another opinion(s), I was so excited when I got my 2023 Duramax in May 2023, great vehicle with good mileage but it was a fest until I noticed that truck burns oil, 3/4 QT per 2500 miles. Second oil change of ACDelco 0w20 DexosD oil with OEM filter and it keeps burning. I am not seeing oil leaks anywhere.
Since GM released a TSB saying that 1QT per 1000 miles is normal for Duramax 3.0, dealer are not doing a thing about it. It leaves me with a question, I assume that rings are the problem and if I am to run approved Dexos D oils, I will just keep burning and need to carry 2 QT of oil on the long cross country trips? Switching to 5w30 will not address a thing?

Assuming the PCV works, It may be the 0w20. High oil temps and thin oil can cause excessive evaporation.

I want a new AT4 with the 3.0 and if I got one, I’d immediately change the oil and fill with M1 ESP 5w30 or a synthetic 10w30 CK-4.

You can try a different oil like the ones above to see if the consumption goes away or is reduced.

 

[wwillson]

I assume that rings are the problem

Why would you assume the rings are the problem? Did you read this entire thread?

 

[smokey_2020]

@wwillson I assumed rings on mine only because some owners of LM2 report zero burn driving on highways 75+ with strong headwinds. EGT cannot be completely different when I drive and when they drive. I drive 70+ and it burns like 1970 Yugo.

 

[wwillson]

@wwillson I assumed rings on mine only because some owners of LM2 report zero burn driving on highways 75+ with strong headwinds. EGT cannot be completely different when I drive and when they drive. I drive 70+ and it burns like 1970 Yugo.

What are your sustained EGTs?

 

[MSCH]

Guys, need another opinion(s), I was so excited when I got my 2023 Duramax in May 2023, great vehicle with good mileage but it was a fest until I noticed that truck burns oil, 3/4 QT per 2500 miles. Second oil change of ACDelco 0w20 DexosD oil with OEM filter and it keeps burning. I am not seeing oil leaks anywhere.
Since GM released a TSB saying that 1QT per 1000 miles is normal for Duramax 3.0, dealer are not doing a thing about it. It leaves me with a question, I assume that rings are the problem and if I am to run approved Dexos D oils, I will just keep burning and need to carry 2 QT of oil on the long cross country trips? Switching to 5w30 will not address a thing?

give you my expert opinion... a quart of oil in 3000 or so miles is nothing to worry about.
fact of the matter is some engines of the same type will use more oil than others of the same type and nothing is wrong with them.
could be tolerance stack up in a production vehicle, could be situational or a combination of both..
Yall have already covered the workload thing, yes that can make a difference.
different brands and viscosities of oil might make a small difference
but I'd be willing to bet if you add a quart of oil when the truck needs it
and change the oil when you are supposed to
your truck will run into the hundreds of thousands of miles and the oil consumption won't change one bit over that amount of time.

 

[panthermike]

I test drove one of these recently and absolutely loved it. It's something I'm considering for sure, but the oil consumption being normal and from what I've read fairly common seems strange to me.

 

[MSCH]

interesting what GM terms acceptable oil usage in the 6.6 Dmax engine... compared to seeing someone thinking a quart per 3000 miles is excessive.

quote"
For Engine RPOs LMM, LML and LGH
The maximum oil consumption for the 6.6L Duramax™ Diesel engine (RPOs LMM, LML and LGH) is 1.18 liter (1.25 qt) within 379 liters (100 gallons) of fuel used. For heavy towing applications (9 mpg/26.1 L/100 km (Liters per 100 kilometers)), this correlates to a consumption of 1.30 liter (1.38 qt) per 1000 miles.



For Engine RPOs LBZ, LB7 and LYY
The accepted rate of oil consumption for the 6.6L Duramax™ Diesel engine (RPOs LBZ, LB7 and LYY) is 0.946 liter (1 qt) within 379 liters (100 gallons) of fuel used. This rate only applies to vehicles under warranty, maintained in accordance with the appropriate maintenance schedule, driven at legal speeds and within
design intent of the vehicle.

the rest is here.. chrome-extension://oemmndcbldboiebfnladdacbdfmadadm/https://static.nhtsa.gov/odi/tsbs/2016/MC-10137617-9999.pdf

 

[smokey_2020]

What are your sustained EGTs?

I am searching eBay for a used iDash to watch temps and regens. Not yet found one.

 

[MSCH]

I am searching eBay for a used iDash to watch temps and regens. Not yet found one.

I've found quite a bit of emotional security from not paying attention to the numbers generated.

 

[dbphillips]

I am searching eBay for a used iDash to watch temps and regens. Not yet found one.

You likely won't, they haven't been out that long.

 

[dbphillips]

give you my expert opinion... a quart of oil in 3000 or so miles is nothing to worry about.
fact of the matter is some engines of the same type will use more oil than others of the same type and nothing is wrong with them.
could be tolerance stack up in a production vehicle, could be situational or a combination of both..
Yall have already covered the workload thing, yes that can make a difference.
different brands and viscosities of oil might make a small difference
but I'd be willing to bet if you add a quart of oil when the truck needs it
and change the oil when you are supposed to
your truck will run into the hundreds of thousands of miles and the oil consumption won't change one bit over that amount of time.

I'll give you my professional opinion as a mechanical engineer. Just like the overboosted Volvo 4 cylinder with 0-20W, a significant number of engines showing oil consumption will score the pistons and self detonate.

Just because a lawyer says it's normal doesn't make it so. That much consumption indicates there wouldn't be so many people claiming no usage at all. Those that burn 1qt per 1000 miles are outliers. The question is where is the break point between the two.

 

[MSCH]

I'll give you my professional opinion as a mechanical engineer. Just like the overboosted Volvo 4 cylinder with 0-20W, a significant number of engines showing oil consumption will score the pistons and self detonate.

Just because a lawyer says it's normal doesn't make it so. That much consumption indicates there wouldn't be so many people claiming no usage at all. Those that burn 1qt per 1000 miles are outliers. The question is where is the break point between the two.

talking 3000 miles per quart on aDuramax, and not about Volvo's. If you were an engineer you should understand that you just did a apples to oranges comparison.

Carrying it on a little further, why would the rings get scored simply because of oil consumption?
Would more oil getting past the rings cause the piston rings to become scored?

 

[dbphillips]

talking 3000 miles per quart on aDuramax, and not about Volvo's. If you were an engineer you should understand that you just did a apples to oranges comparison.

Carrying it on a little further, why would the rings get scored simply because of oil consumption?
Would more oil getting past the rings cause the piston rings to become scored?

If oil is getting by the rings, then the cylinders aren't getting properly lubricated. Rather obvious.

Not apples and oranges at all. At most, tangerines and oranges. Mechanically, there is nothing different between the interfaces. Volvo has a smaller engine with the same dumb energy saving tech and a 5000# towing capacity. Babymax has 50% more displacement and 50% more capacity. They even use almost the same oil and have the same displacement per cylinder. The biggest difference is compression ratio.

But the fact remains; some engines are not right. I proved it with Volvo: significant oil consumption at 35k miles, engine replaced at 50k, now at 120k and still no consumption. And it was passed on to my son, so driven even harder.

The only people with the data correlating oil consumption to cylinder scoring are the manufacturers. It's going to take a class action to get a law passed to require the data be published.