How does the GM oil life monitor work?
Starting with the 2010 model year, GM instituted an oil life monitor that calculates remaining oil life based on the factors listed below. The algorithm assumes that you’ve used the correct DEXOS oil and viscosity as recommended in the owner’s manual AND assumes that you check and maintain the proper oil level at all times. If you use a non-DEXOS oil, wrong viscosity or let the engine run low on oil, the oil life monitor will no longer be accurate and you risk driving too long between oil changes.
What the oil life monitor tracks
After each oil change reset, the GM oil life monitor tracks
• Engine revolutions- The GM oil life monitor starts with a factory preset number of engine revolutions stored in memory. Every time the engine is started and run, the oil life monitor tracks the number of revolutions run and subtracts those from the factory programmed target.
• Engine temperature— The algorithm incorporates multipliers that reduce the number of engine revolutions, and thus remaining oil life, based on how far engine oil temperature varies from normal oil temperature. If the PCM records an engine temperature above 260°F, the remaining oil life will immediately show 0% remaining life. Cold starts reduce oil life and the algorithm takes that into account by reducing the number of revolutions accordingly.
• Miles since last reset—The monitor records miles traveled since the last oil reset and maintains a MAXIMUM value of 7,500 miles for ALL 2013 and later GM vehicles (except the Volt) before it show 0% remaining oil life.
Time—The oil life monitor records the amount of time the engine runs since the last oil change reset. The time tracking is a liner measurement and decreases remaining oil life on a straight life basis in conjunction with the other tracked variables. The monitor will show 0% after one year regardless of miles driven, engine revolutions or time run.
When to change oil on a GM vehicle
Regardless of what self proclaimed experts, oil distributors or oil companies may claim, the maximum oil life on GM vehicles (except for the Volt model) is 7,500 miles or less. Oil life depends on time, miles, temperature and engine revolutions. Do not be fooled into thinking you can go beyond this limit.
Engine overheating will deplete remaining oil life
If the engine coolant temperature exceeds 260°F, the oil life monitor will immediately to to 0% remaining oil life.
©, 2017 Rick Muscoplat
Posted on by Rick Muscoplat
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