Understanding the Oil Life Monitor: Benefits and Maintenance

How an Oil Life Monitor Works: Ensuring Optimal Engine Performance

Modern automotive technology has vastly improved the way we maintain our vehicles, making it easier and more efficient to keep engines running smoothly. One such advancement is the oil life monitor (OLM) system. This intelligent system helps vehicle owners determine the optimal time for an oil change, ensuring that the engine oil remains effective in lubricating and protecting the engine. This article delves into the workings of an oil life monitor, its benefits, and its impact on vehicle maintenance.

An oil life monitor system tracks how you drive, not the condition of the oil

An oil life monitor (OLM) is a sophisticated system integrated

Some oil life monitor systems tell you how much oil life is left in a percentage. Others just tell you it’s time for an oil change

into a vehicle’s onboard computer that calculates the remaining useful life of the engine oil based on how you drive. It provides real-time information to the driver, indicating when it is time to change the oil based on various factors rather than a fixed mileage interval. This approach ensures that the oil is changed only when necessary, maximizing its efficiency and lifespan.

How Does an Oil Life Monitor Work?

The carmaker conducts extensive oil life testing under varying conditions to determine how long the recommended oil will last. They compile the result to build a predictive algorithm to calculate how long the oil will last in your particular engine based on your driving habits. However, the algorithm is based on two assumptions: 1) That you’ve used the recommended oil type and viscosity shown in your owner’s manual, and 2) You check your oil level on a regular basis and top off as recommended.

If you don’t use the recommended oil and don’t check oil level and top it off, all bets are off, and you’re on your own trying to figure out when to get your oil change.

Here’s what the oil life monitor tracks

Each carmaker has its own usage tracking methods, but these are the most commonly tracked usage statistics:

• Engine temperature— Oil life degrades much faster as the engine temperature rises above normal operating temperature. A single incidence of engine overheating can reduce oil life to 0
• Engine RPM— Higher RPM operation can degrade the anti-wear additives faster, so some OLM systems track total RPM and high engine RPM
• Number of Cold Starts and ambient temperature when started— Cold starts are especially hard on oil due to the rich fuel mixture and water byproducts. Hence, tracking the number of cold starts is useful in determining oil life.
• Length of the trip in miles and minutes— A longer trip warms up the oil and evaporates off the fuel and water in the oil. A longer trip also filters out more soot contaminates from a cold start.
• Engine load, towing, hauling heavy loads— High engine loads cause more viscosity index improver shearing, which reduces oil viscosity, so engine load correlates to oil life
• Idle time— Idling is also hard on oil since it doesn’t circulate as fast and doesn’t cool as well, reducing oil life.
• Highway versus city stop and go— Highway traffic is generally easier on oil, unless you’re traveling for hours at highway speed through desert conditions. City stop and go traffic, is incredibly hard on oil, so tracking how you drive determines how long your oil will last.

Calculation of Oil Life: Based on the analyzed data, the OLM calculates the remaining oil life as a percentage. This percentage reflects the oil’s ability to continue providing effective lubrication and protection.

Driver Notification: The OLM communicates with the driver through the vehicle’s dashboard or infotainment system. It typically provides a visual indication, such as an oil life percentage or a maintenance reminder, alerting the driver when an oil change is necessary.

The GM Oil Life Monitoring System

GM’s Oil Life Monitoring system (GMOLM), for example starts with a pre-determined number of engine revolutions and miles stored in memory. GMOLM starts counting down from that pre-determined number as soon as you start the engine after an oil change reset. GMOLM also tracks engine temperature and adds a multiplier to the countdown based on how far oil temperature varies from “normal.” For example, if you drive with an overheated engine above 260°, the GMOLM will immediately reduce the remaining oil life to 0%. GMOLM also tracks the number of operating hours and miles, causing the oil change light to come on at 7,500 miles or one year, whichever comes first.

Ford’s Intelligent Oil Life Monitor is similar to the GMOLM, while the Fiat-Chrysler system also adjusts for the amount of ethanol in the fuel.

VW and Audi oil life monitor

VW and Audi monitor those same factors as GM, Ford and Chrysler but also look at the oil’s thermal load using a combination of oil level and oil temperature sensors and adjusting with a fuel consumption mileage and time algorithm. Measuring oil level land fuel consumption is important because the GM, Ford, and Chrysler systems DON’T track oil levels. If you run those engines when low on oil, the oil life monitors will be inaccurate. So, the VW and Audi systems factor in the additional wear caused when you drive with less than the recommended oil level in the crankcase.

When you can’t trust an oil life monitor system

• You use a different grade of oil. If your vehicle requires synthetic oil and you use conventional, you can’t trust the oil life monitor.
• You use a different oil service classification. Most European engines require an ACEA class oil, while most domestics and Japanese require an American Petroleum Institute (API) SN PLUS or International Lubricants Standardization and Approval Committee (ILSAC) GF-5
• You use a different oil viscosity
• You use a long life synthetic oil with an oil filter not rated for long life

©, 2019 Rick Muscoplat