Sensors Could Warn You When to Change Your Oil

(NUI) - Wise motorists will tell you that if you do nothing else for your vehicle, you should change the engine oil regularly. For many cars, this means every 3,000 miles. But, as the American Society of Mechanical Engineers points out, scheduled maintenance cannot predict when oil will break down ahead of time. This means a lot of serviceable oil from vehicles that see less strenuous use is thrown out.

"That's why a number of efforts are aimed at developing on-board monitors to measure oil quality in real time or, at least, to base predictions on specific, observable conditions," ASME says in an article in its publication Mechanical Engineering.

According to some forecasters, a reliable means of monitoring the condition of engine oil could save millions of quarts of oil a year.

Although industrywide minimum standards exist for acceptable engine-oil quality, engine-oil performance can vary widely according to individual driving habits, driving conditions and engine design.

For instance, a vehicle used for short trips in cold weather never warms up properly, so its engine crankcase is subject to a hostile environment of condensed fuel and water vapor. On the other hand, a car that is driven across the desert at or above the speed limit with a trailer in tow will run at high temperatures, causing the oil to thermally degrade and thicken.

According to Mechanical Engineering, auto manufacturers recommend scheduled oil changes along very conservative time frames. Changing the oil every 3,000 miles may not be necessary -- and it can often be wasteful.

On-board oil monitoring devices, which signal oil degradation to the driver via the dashboard, are designed to take waste out of routine vehicle maintenance.

The sensor measures oil aging by monitoring the oil's dielectric constant, which increases as molecules break down and additives deplete with use. A potential application of the sensors is to detect the presence of contaminants in the oil such as water or coolant. The devices are still in the research and development stage.

Meanwhile, continue to be on the safe side: Change your oil every 3,000 miles.

For more information on mechanical engineering technology, visit the ASME Web site at

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