Oil consumption

[Early]

My '18 Yukon Denali's got 25K miles on it. Yesterday, traveling the interstate at 75mph, I got an oil warning to add oil. I checked the usage and still had 51% left. The dipstick showed over a quart low. It's not leaking and there isn't any blue smoke at start-up. Any thoughts?

Thanks in advance.

 

[07Burb]

I know your dash says 51% life left, but how many miles do you think you've driven since your last oil change?

 

[iamdub]

My '18 Yukon Denali's got 25K miles on it. Yesterday, traveling the interstate at 75mph, I got an oil warning to add oil. I checked the usage and still had 51% left. The dipstick showed over a quart low. It's not leaking and there isn't any blue smoke at start-up. Any thoughts?

Thanks in advance.

The OLM (Oil Life Monitor) has nothing to do with the volume of oil the engine contains. If you only had 51% of the amount of oil your engine required, you'd be about 3 quarts low. The OLM estimates the usable life of the oil based on temperature, engine loads, run time, and other factors. I'm not totally sure about the newest generation, but with the older trucks it's widely known to change the oil on a more regular basis rather than when the OLM says to (at 0%). The OLMs may have better programming now, but I'd still stick to a mileage schedule.

Your engine is burning a little oil. At this point, I'd guess that it's either your engine may still be breaking in at only 25K miles and it's consumption will decrease or your OLM is a bit generous (like with the previous generation) and you have a lot of miles on some cheap oil and it's starting to burn off.

Ask 100 people and you'll get 100 different recommendations. Mine is to change it every time you rotate your tires which should be every 5-6K and use full synthetic. If it's still consuming a quart or so of synthetic within that 5-6K interval, then I'd kinda be concerned. Don't expect much from GM because they consider upwards of 1 quart burned for every 2,000 miles to be acceptable. At a normal 5-6K mile OCI, you'd be replacing half your oil between each oil change.

 

[SnowDrifter]

I'm of the personal opinion that OLMs aren't a great guide. They're a pre programmed estimation of the serviceability of your current oil based on driving factors such as temperature, load, cold starts, idle time, etc. It doesn't directly measure anything with the oil - 'tis but a best guess. Use a different oil / filter - or drive in some fringe scenarios, and the OLM will be grossly inaccurate. But I digress

That calculation which is numerically displayed to you as a percentage isn't your oil level. Only the estimated condition of the oil that's in there. Keeping it topped up is on you.


What oil are you running and for how long? High NOACK stuff is apt to burn off and evaporate. And low HTHS oils will tend to let more past the rings too. So oil used is one consideration

Next one is driving conditions. High RPM loads will burn more oil period. Both coming past the rings and through the PCV system. 4cyl mode will also counter-intuitively burn more oil due to the behavior of the lubrication system when it's activated. The reason for that is - the cylinders are still lubricated by an oil sprayer as they're still moving. But cylinders and rings need pressure to expand and seal appropriately. Fun fact: That's why long idle time is so bad and if you had to run the engine for say 1000 hours; it would cause you less wear to run for that long at 1500 rpm than at idle. Without combustion pressure, oil fairly freely makes it past the rings.

Could also be a manufacturing defect within the engine - newer rigs from almost all manufacturers are suffering from oil consumption problems as ring thickness, spacing are adjusted to trim weight. Unfortunately, unless it's truly hugely excessive, the dealer will just tell you to top up and go on your merry way. If it's more than a quart every 1k, then they'll give you some attention.


Edit: if you suspect carbon buildup in the deactivated cylinders - put some high octane gas in there and drive the everloving piss out of the truck. Hook up an 8k trailer and go up a few mountain passes or something. Get cylinder temps up and hold them there - will help burn up / clear out carbon. The higher octane is just to prevent spark retard and preignition as stuff heats up

 

[07Burb]

Don't expect much from GM because they consider upwards of 1 quart burned for every 2,000 miles to be acceptable. At a normal 5-6K mile OCI, you'd be replacing half your oil between each oil change.

This statement here is exactly why I asked the question I did. And I put NO stock in my OLM to determine when I change my oil. I change it at 3,000 miles regardless of the OLM. Mine used to consume oil until i had the AFM system tuned out. Since that point, my oil consumption has been virtually 0. A possibility for what's going on with your ride, as well? Also, the scenarios @iamdub pointed could also be the case @SnowDrifter also brings up good points. Long story short, could be a number of things.

 

[SnowDrifter]

While my mind is working, check PCV system too. If it's not free flowing, it'll jack up crank case pressures and force oil through seals/gaskets in what should be a net 0 pressure environment - crankcase pressure vs. ambient air pressure

 

[Early]

I know your dash says 51% life left, but how many miles do you think you've driven since your last oil change?

About 6,000 miles

 

[HiHoeSilver]

About 6,000 miles

Time for a change. A quart low is pretty average at 6k miles.

 

[iamdub]

I agree with Nate. I don't think you have a problem and the consumption may get better.

 

[Early]

Time for a change. A quart low is pretty average at 6k miles.

Just found out there's a Service Bulletin for the 10-speed transmission (hard shifting) in this thing so I'm taking it to the dealer next week. I'll ask them about the oil consumption then.

Thanks for your response.

 

[iamdub]

Just found out there's a Service Bulletin for the 10-speed transmission (hard shifting) in this thing so I'm taking it to the dealer next week. I'll ask them about the oil consumption then.

Thanks for your response.

Please post back. I'm sure I'm not the only one interested to hear what they tell you about the consumption.

 

[HiHoeSilver]

Please post back. I'm sure I'm not the only one interested to hear what they tell you about the consumption.

Betting heavily on "that's normal"

 

[iamdub]

Betting heavily on "that's normal"

Agreed, and maybe even backed up by them quoting GM's specified allowance, reinforcing that the OP's amount of consumption is very, very small.

 

[Ponch]

My '18 Yukon Denali's got 25K miles on it. Yesterday, traveling the interstate at 75mph, I got an oil warning to add oil. I checked the usage and still had 51% left. The dipstick showed over a quart low. It's not leaking and there isn't any blue smoke at start-up. Any thoughts?

Thanks in advance.

Wonder if it could be AFM or what they call DFM now?

 

[Bob2C]

Get a range device. No more V4 mode, no more oil consumption.


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[07Burb]

Get a range device. No more V4 mode, no more oil consumption.


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Not necessarily true. @89Suburban has the Range device and still has considerable oil consumption.

 

[89Suburban]

Not necessarily true. @89Suburban has the Range device and still has considerable oil consumption.

I think the high mileage of over 300K isn't helping. But the range device certainly cuts off the V4 mode. Too little too late maybe, but I am trying to keep her going and take it easy on her. I love her.

 

[Bob2C]

Your probably right about the high mileage causing the oil burn. I have been running the range device from new and have no oil burn. Now have 14k miles on it. The only issue I have is that damn rough idle while in drive. I know there a tsb on the motor mounts for it. Just have to bring it in for them to look at it


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[Doubeleive]

i'm on the opposite end of the spectrum here, I drive both my trucks fairly hard. The Silverado has 242k and doesn't burn a drop, oil level starts on the line and ends on the line, the Denali is the same engine has about 40k on it no oil consumption.

 

[iamdub]

I think the high mileage of over 300K isn't helping. But the range device certainly cuts off the V4 mode. Too little too late maybe, but I am trying to keep her going and take it easy on her. I love her.

Ever done a compression test?