Oil Life Meter

[svaneld]

This may be a dumb question but how is my truck figuring th 50% oil life reading that I get? From what I can tell it is based directly off of miles since I was at 1500 miles when it showed 50%. I have heard that it is calculated differently so I wanted to make sure. I use synthetic so I will usually change my oil every 4500-5000 miles. If it is calculated off of miles I was wondering if you can adjust it to go off of 5000 miles instead of 3000. It is annoying if I hit the 0% and it dings at me all the time. When it has hit 0% I have checked my oil and it is clean as a whistle and still full. My truck is a 2005 Sierra SLE 5.3 with 83k miles. Thanks for the help.

[scottiemac]

From the manual:

"Your vehicle has a computer system that lets you know when to change the engine oil and filter. This is based on engine revolutions and engine temperature, and not on mileage. Based on driving conditions, the mileage at which an oil change will be indicated can vary considerably. For the oil life system to work properly, you must reset the system every time the oil is changed."

 

 

 

I think this is overly simplistic but I'd heard it takes into account cold starts, short drives, etc. to do the calculations. If you do lots of highway driving it would likely be longer and if you make a lot of trips that don't let the engine warm up it will be shorter.

 

 

 

Good luck.

 

 

[svaneld]

That helps a lot. Thanks for the info. Guess I should read my manual closer before I ask questions huh . Thanks again.

[dewfpo]

It's based on readings from a variety of sensors and is a fairly complex algorithm (formula). Depending on engine and driving conditions you may be able to drive 45 miles before it changes 1% and other times you may be able to drive 85 miles between each percent change. Many change their dino oil by the OLM and have done so for years and haven't had any issues. I can't even imagine it going to 0% at only 3,000 miles even under very severe conditions but I guess it's possible if you beat it badly enough for a long enough period of time.

 

With synthetic oil, you should consider 5,000 miles as the bare minimum under the worst driving conditions for long periods of time. 7,500 - 10,000 miles is more typical on good quality synthetic. Unfortunately, there's no way to tell the OLM your using synthetic and not dino so it can't be factored into the algorithm.

 

Cheers,

 

DEWFPO

[txab]

There is a little Elf under the hood with a calculator.......

 

Oil Life Monitor

[svaneld]

There is a little Elf under the hood with a calculator.......

 

+1 I like that

[dlstewart01]

The OLM does NOT just monitor engine revolutions. Each specific engine has a stored maximum "bank" of set engine duty cycles (revolutions) between OCIs, reset by the user at time of service. Each time the PCM fires, it subtracts the number of revolutions from the bank. When the bank = 0, the "Change Engine Oil" or oil light illuminates. Outside air temp, coolant temp, cold soak time, throttle load, vehicle speed, etc. are all accounted for in an effort to predict oil temperature, which in turn assess an exponential penalty factor. If the oil temp is above or below the standard algorithm allowance, the amount of degradation increases and is subtracted from the bank value at a higher rate. Hence, if you drive short trips in cold temps, the OLM ticks away faster. If you track your Vette with high rpm/loads, the OLM ticks away faster. If you tow, well you get the idea...

 

The ONLY thing the OLM cannot account for is a mechanical engine fault. If you have a leaky air filter or a coolant leak, the OLM will never know or change it's signaled OCI. This is where and oil condition monitor would be superior. GM chose this route for simplicity/cost. They are willing to stake a 5yr/100K powertrain warranty on it, so it can't be too terrible.