How Does an Oil Life Gauge Function?

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    • Oil is the lifeblood of a car's engine. It helps the engine stay clean and provides lubrication for its many moving parts. One of the most basic edicts of car maintenance is making sure the oil is replaced on a regular basis. Older oil has a lot of dirt in it and does not protect the engine as well. Plus, older oil is more likely to overheat and can turn into a sludge-like substance that can lock up your engine. The typical rule with oil changes is that the oil should be changed once every 3,000 miles or every three months, whichever comes first. This time-frame is longer if you're using synthetic oil, which can last longer than traditional types. However even this rule of thumb is imperfect as the true lasting time of engine oil is affected by many things like weather conditions and driving habits that can either break the oil down faster or make it last longer. Some cars have started using oil life gauges as a way of predicting when the oil is breaking down and being more specific on when it needs to be changed. Many of them solely rely on mileage numbers when predicting oil life, but there are several different types of gauges in development as well, and they work in different ways.

    The Kavlico Guage

    • The Kavlico oil sensor measures the dielectric constant of engine oil, which increases as the oil gets older and starts to breakdown. As friction and temperature in the oil increase, the dielectric constant gets higher and the sensor sends a higher voltage to the car's computer. The sensor is made of two electrodes that are parallel to each other. There is a gap between them that is filled with oil. There is a sensing element on one electrode that is in direct contact with the oil and a circuit that converts the reading of the sensing element into voltage. There is also a housing that protects the unit. It is normally located in the oil pan or the output-side of the oil filter. It has become more commonly used on large diesel engines.


    • The Bio-MEMS group uses an iridium dioxide sensor in engine oil that can measure the pH level of the oil. The sensor is made of three electrodes contained in an alumina shell with a ceramic bottom that is filled with a solvent that never mixes with the oil itself. The sensor also measures impedance, which is the resistance and capacitance of the oil, as well as the presence of added materials in the oil such as traces of metal particles. The measurement of these multiple factors is intended to result in a more accurate estimation of your engine oil health.

    General Motors

    • GM has designed an Oil-Life System that, unlike its contemporaries, does not use sensors in the engine oil at all. The engine's computer estimates the rate of oil degradation from data already being collected from systems inside the vehicle. Using a math model, the computer crunches the numbers it receives regarding average vehicle speed, engine temperature, coolant and oil temperature, and other factors and customizes its oil-changing recommendations depending on the type of engine and transmission as well as the driver's habits behind the wheel. Some companies have used GM's math model and combined it with oil sensors in a dual approach to try to get even more accurate predictions of a car's overall oil health.

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