Why Engine Oil Turns Black?

Engine oil lubricates the engine and prevents overheating, which lets the engine’s parts work well without getting too hot. As oil gets older, it starts to lose its ability to protect, so it needs to be changed. But just because engine oil turns black doesn’t always mean it needs to be changed. Here’s how to know when to change your oil.

Engine oil Comes in various types and grades; new engine oil is usually transparent and yellow, like honey. It doesn’t stay the same color for long because each time it’s heated, the color gets darker.

What Turns Engine Oil Black?

Heat Cycle

When your engine reaches its normal operating temperature, which is usually just below 220 degrees Fahrenheit, and then cools down again, this is called a “heat cycle.” Every time you go to the store, drive to work, or bring your kids home from activities, your engine will heat up and then cool down. The engine goes through more heat cycles the more trips you take.


Not only does heat change the color of engine oil, but so do contaminants. Small pieces of metal from engine parts will break off and move around in the oil. The road dust and dirt that doesn’t get caught by the oil filter is another thing that makes the oil get darker.


Additives are chemical compounds that are put into engine oil to make it work better. These additives, which can be found in both petroleum-based and synthetic oils, are needed by modern engines. Your engine will break if you don’t add anything to it. With them, your oil will get darker no matter how many heat cycles or abrasives you use.

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How To Know if It’s time to change the Oil?

The best way to know when it’s time to change the oil in your car is to look at the maintenance schedule in your owner’s manual. If your engine needs synthetic oil and you can drive normally for 10,000 miles without changing the oil, then your oil is probably fine. But if you drive a lot of short trips on dusty roads or in extreme temperatures, you’ll need to change your oil more often. Again, check your owner’s manual for the right time between oil changes.

Warning Signs

Just as engine oil will change from amber to black over time, there are other signs that it needs to be changed. Some of these signs could point to a problem that is related to another.

For example, if the engine oil has more than the normal small amount of water in it, it will look milky and thin when you pull out the dipstick. The most troublesome thing is when water droplets stick to the end of the dipstick.

This big problem might have been caused by driving through flood water. Don’t start the car if this is the case. At the very least, you’ll have to take out the oil and oil filter and clean the oil pan. Next, put in new oil and an oil filter. Drive your car for a few hundred miles before changing both again. But for a car that has been underwater for a long time, you’ll need to take the engine apart completely.

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Another thing to think about is oil that looks like foam or milk and has a color like cream. This is a clear sign of a leaking head gasket, which can also be seen when white smoke comes out of the exhaust or when more coolant is used. Fix what needs to be fixed, and then give your engine new oil and a new filter.

When the oil in your engine turns black, you may or may not need to change it. Keep an eye on the color of your engine oil, though, because it can tell you about other problems. If you’re not sure what to do, check your owner’s manual or talk to a trusted mechanic.

1 thought on “Why Engine Oil Turns Black?”

  1. I have been using my Altima without any major problems. But when I reactivated the air-conditioner and ran it with the AC for some distance then stopped. When I tried to restart the engine it refused to start. I didn’t see any obvious sign of problem so I decided to wait for some time. Then it started the next time I tried to start it. I didn’t dare switch on the AC again. What could be the problem? Thanks!


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