Why does my car's engine oil turn black?
Content
Motor oils are usually amber or brown in color. What happens is that over time and mileage, the viscosity and color of the grease tend to change, and when the grease turns black, it is doing its job.
too saturated with pollutants to protect your car's engine and needs to be replaced. This is not necessarily true.
The discoloration is a by-product of heat and soot particles, which are too small to wear out an engine.
The best and most recommended is to follow the oil change recommendations given in your car manufacturer's or engine oil manufacturer's manual, and not change it just because it has turned black.
Why does engine oil turn black?
There are some factors that can cause oil to change color. These are the factors that cause engine oil to turn black.
1.- Temperature cycles naturally darken engine oil.
Your car's engine reaches normal operating temperature (usually between 194ºF and 219ºF), thus warming up the engine oil. This oil is then cooled while your vehicle is stationary.
That's what a temperature cycle is. Repeated exposure to periods of high temperatures will naturally darken the engine oil. On the other hand, some additives in motor oil are more likely to darken when exposed to heat than others.
In addition, normal oxidation can also darken engine oil. Oxidation occurs when oxygen molecules interact with oil molecules, causing chemical breakdown.
2.- Soot changes the color of the oil to black.
Most of us associate soot with diesel engines, but gasoline engines can emit soot too, especially modern direct injection vehicles.
Soot is a by-product of incomplete combustion of fuel. Because soot particles are less than a micron in size, they generally do not cause engine wear.
All this means that darkening of the oil is a normal process during normal engine operation. This fact not only does not prevent the oil from performing its functions of lubricating and protecting engine components, but also indicates that it is performing its function correctly.
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