The oil light can indicate an issue with the oil level or oil pressure—sometimes both. If the engine loses oil pressure, the oil light is going to come on. That light will be red because you have to shut the engine down quickly. If the oil pressure is too low, there will be internal damage to the engine. The damage would be similar to driving without oil in the engine.
To clarify, you can be low on oil and still have oil pressure. The oil light may not let you know that you are low on oil—in some cars, only checking the level with a dipstick can tell you if you are low on oil. (One new technology in some of the higher end cars, like some BMW and Mercedes models, uses no dipstick. Instead, a sensor inside the engine reads the oil level and indicates its level. Most cars still have a dipstick.)
Even when you’re a quart or two low on oil, you still have enough oil in the engine to produce oil pressure. In that case, the oil light might not come on because adequate oil pressure exists. However, the lower your oil level, the more stress and damage to your engine may occur. Potentially, you could have a low oil level and no indicator light to warn you. That’s why regular oil changes are so important.
Having a sufficient oil level provides several benefits. Lubricating the engine is the oil’s primary job, but it also assists in engine cooling. Most people do not think about the cooling properties of the motor oil but that is an important function as well. The oil moves heat from critical moving parts as it circulates through the engine.
Using the correct oil type is also important to maintain maximum fuel economy as using the wrong oil can lower your fuel mileage.
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