Appropriate oil life

calgator73 · December 20, 2015

Drove 1,225 miles in 19hrs yesterday (two fill-ups) Engine oil life decreased from 34% at the beginning to 16%. Does that seem right?

LongrangeLauber · December 20, 2015

About right, if you do 1225/7500= 0.163 then 0.163X100= 16.3%. 34-16= 18%.

That would be for perfect driving conditions. Gotta factor in rev ups(hill climbs), temperature, humidity, road conditions, etc.

calgator73 · December 20, 2015

Thanks... Didn't realize the basis for the oil life calculation was 7500 miles. Diesels must be really rough on oil. My 5.3 would only decrease like that if it never warmed up.

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LongrangeLauber · December 20, 2015

Oh wow, didn't realize that it was under the HD k2 section. I was going off of the gas engine recommended mileage. I belive the Dmax is every 10k miles, so yeah it did decrease faster than it should. All I saw on tapatalk was 2014+ k2 section lol

calgator73 · December 20, 2015

That is okay. My 2014 would normally hit about 11k on oil life

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ShotgunZ71 · December 20, 2015

I'm at almost 4800 miles and am showing 35% oil life and 26% DEF.

calgator73 · December 21, 2015

Thanks for the response

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newdude · December 21, 2015

Thanks... Didn't realize the basis for the oil life calculation was 7500 miles. Diesels must be really rough on oil. My 5.3 would only decrease like that if it never warmed up.

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GM oil life algorithm is not based on mileage but it does have a mileage cap at 7500 miles.

Condition/Concern
Since 2010 all GM vehicles have been equipped with the oil life monitor (OLM) system

The monitor calculates the percent of oil life remaining, based on 3 pathways

The OLM starts its calculation for all pathways after the first 50 miles to account for marshalling and time before sale. Subsequently, calculations begin immediately after each reset.
Recommendation/Instructions
Oil Life Monitor Calculation Pathways:

Engine revolutions- Oil life starts with a fixed number of revolutions and will decrease with each revolution. Cold / hot coolant temp readings have multipliers that reduce engine revolutions pathway quicker depending on how far from the normal oil temperature the vehicle is operating.

Note: If engine coolant temp gets above 260F, engine overheat condition, the oil life will go to 0%.

Mileage from last reset – Starting with MY 2013, the OLM is capped at 7500 miles for all GM powertrains except the Volt. In perfect conditions a vehicle would reach 7500 miles from the last reset and the oil life left would be 0%.

Time- This pathway is a liner function, a fixed decrease in oil life for a given time after the oil life is reset. The oil life will drop to 0% after 1 year regardless of the amount of engine revolutions or how many miles since the reset.

Note: The Volt uses a 2 year timer instead of 1 year. It also uses the engine revolution counter. It does not use the mileage pathway to count down.

calgator73 · December 22, 2015

I have to pull the service tickets for my wife's lacrosse... Swear it's going longer.

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Cowpie · December 23, 2015

GM has their OLM calculation thing going on, but I have mine. My 6.0 gets changed at 6000 miles. The manual makes it very clear that any severe service may require more frequent oil changes than OLM suggestion. I can't even leave my driveway without encountering one of the severe service classifications according to the OEM. And the OLM cannot calculate for everything. It doesn't have a clue if I am in dusty conditions or not, for one. If the GM OLM is using some form of "algorithm" to determine things, that is fine. It still cannot measure everything.

On diesels, I have generally gone 10-11K on smaller stuff like the 2.8L diesel in a 2006 Jeep Liberty, up to 25,000 miles on my commercial trucks. Since all the OEM's have dialed back the amount of EGR that is getting ingested by motors now since the advent of SCR, there is really no reason a diesel could not go 10-11K on an oil change for the average user. I wouldn't pay any attention to an OLM for a diesel either.