# OLM just confuses me.



## jsusanka (Jan 31, 2011)

Went out of town the past week and my cruze sat for about 8 days. Before I left the OLM was at 42% and then when I drove it today it was at 40% and I drove it about 25 miles on the highway and when I came back it was at 39%. 

I don't get why it would go down when I am not driving the car. Then I barely drive it and it drops another percent. 
Car is running great (knock on wood) and still doesn't go through a drop of oil between yearly changes. 

Temps were nice and cool today too around 60 degrees. 

Maybe I am losing my mind I have been going through a lot lately personally but just wondering if anybody else has seen this behavior from their OLM. 

I have a 2011 1LT.


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## ChevyGuy (Dec 13, 2014)

I'm pretty sure the OLM is programmed to not allow more than a year to pass between oil changes. 8 days is 2% of a year. The short drive might have nudged you over a round-off.


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## Merc6 (Jun 8, 2013)

ChevyGuy said:


> I'm pretty sure the OLM is programmed to not allow more than a year to pass between oil changes. 8 days is 2% of a year. *The short drive might have nudged you over a round-off*.


I also believe this.


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## Tomko (Jun 1, 2013)

_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:_
_1.	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%._

_2.	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%._

_3.	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. _


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## ChevyGuy (Dec 13, 2014)

Tomko said:


> _Oil Life Monitor Calculation Pathways:_


Based on that, it sounds like there's 3 different counters counting down the remaining oil life. The display would show the smallest of the three numbers. Since OP reports going a year between changes, it's probably the time counter that's in the lead in this 3-way race.


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## jsusanka (Jan 31, 2011)

Thanks for all the explanations. I get it now. lol


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