Engine Oil Life Monitors | How they work and what to know.

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 Engine Oil Life Monitors | How they work and what to know.

In the Disney Channel movie, Smart House, a widowed dad and his two kids win a computerized house that's programmed to do everything a busy, young family, especially one without a mom, needs doing—and to the extreme. Personal Applied Technology, or P.A.T., makes meals on command and cleans like a robot, but eventually turns itself into a hologram of a woman that claims to be the kids' mother, and takes total control of their lives. Late-model automotive technology doesn't morph into a Machiavellian mom, but one particular system—oil life monitoring—can possibly cause owners to become too comfortable and less than proactive about caring for their cars.

It's easy to drive for thousands of miles without thinking about how your engine works and worrying about its lifeblood—the oil—so long as it's running well and no dashboard reminder or warning lights are on. It's even easier to think all is well under the hood if your onboard oil monitoring system also tells you on demand the percentage of oil life remaining since the last time you or someone else changed the engine's oil. After all, convenience is one of the joys of owning and driving a new or late-model car.

How Oil Life Indicators Work.
Almost all major automakers employ the use of an oil life monitoring system, also known as oil change or oil life indicator system. General Motors first introduced their system in 1988 and now equips more than 97 percent of their vehicles sold in the U.S. with their GM Oil Life Monitor (GMOLM). This system, like many others, uses a computer-based software algorithm to diagnose an engine's remaining oil life based on a vehicle's operating conditions, and records the number of engine revolutions counting backwards from the system's reset point.

While GMOLM and similar systems also take into account a vehicle's operating conditions (climate, stop-and-go traffic, performance driving, heavy load, highway cruising)—from mild to extreme—by further reducing the number of revolutions from its reset point, the system does not determine the oil's actual condition. Some oil change systems simply calculate mileage since the last oil change and merely notify you once you've driven a certain number of miles. Again, neither system analyzes the actual condition of your vehicle's engine oil.

How and Where You Drive.
Like modern vehicles, engine lubricants have improved over the years, yet driving conditions have, in many locations, gotten worse. In the Los Angeles area, it's not uncommon to commute 50 or more miles one way for hours in heavy, stop-and-go traffic. In other parts of the country, weather takes a huge wear-and-tear toll on oil life and condition.

Severe or extreme driving conditions are generally believed to net between 3,000 and 3,750 miles of oil life, depending on your particular vehicle. According to Valvoline, more than 80 percent of us drive in severe conditions. Consistently moderate driving in a moderate climate could, according to an onboard oil monitoring system, register a maximum oil change alert between 7,500 and 12,000 miles. Hard driving in warm or cold climates might net you only 3,000 miles, or even less. Turbocharged and high-compression engines may also require more frequent oil changes. GM says, "In general, most people that drive a combination of city and highway find that the GMOLM will indicate an oil change every 5,000 to 6,000 miles." Refer to your owner's manual for oil change interval recommendations and guidelines.

The Human and Oil Condition.
Some contend that too-frequent oil changes are bad for the environment or an unnecessary owner expense. Others believe in totally trusting their vehicle's onboard oil monitoring device. Manufacturer suggested oil change intervals are typically conservative, taking into consideration the most extreme, worst-case scenario driving conditions. According to GM, "it is recommended that oil be changed within 600 miles of the change oil light/message (coming on)."

You might decide that a 3,000- to 4,000-mile oil change or switching to longer-life synthetic motor oil is more suitable to your comfort zone. Whatever you decide, it's worthwhile, and recommended by both automakers and oil companies, to regularly check your car's oil level and visually inspect its condition. Even with the advanced and time-tested technology of most onboard oil life monitoring systems, they don't determine the oil's condition. That's up to you or your mechanic.

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