Why does engine oil turn black?

The change in the colour of Engine oil is a normal thing. One should never be worried about its colour transition. The change in colour is because of its dirt, and it is a result that shows your motorcycle is functioning absolutely fine and normal. 


Engine oil turns black because it does its job of suspending dirt particles such as carbon and other contaminants. 


The excessive and continuous exposure to heat tends to blacken or darken engine oil. 


Soot particles also cause the motor oil to darken with time. The modern gasoline direct injection engines also produce soot particles like diesel engines. 


Soot particles are basically the result of incomplete combustion. Very small in size, roughly 70 microns in diameter. 


Should I change my engine oil if it turns black?

Engine oils usually come in a golden or ambre colour. Change in colour with time is something usual. Engine oil should be changed as per your riding activities, road conditions, capacity of motorcycle engine, weather of the place you live in, etc. 


So, you need not change your engine oil as soon as it darkens or blackens. Change it in relevance to your motorcycle and on the basis of the above mentioned factors. 


So in respect to changing engine oil follow the recommendations provided by the manufacturers. The regime they provide is motorcycle specific and thus is expected to be best for your motorcycle. 


Amidst all of these, it is important to remember that choosing the right engine oil grade for your motorcycle is very crucial.  


Related read: How to select engine oil grade for your motorcycle?


Is it bad if my engine oil colour turns black fast?

No, it is not a bad indication if your engine oil colour changes fast. It designates absolute normal functioning of your motorcycle. 


Whereas, no change in colour can be thoughtful. Thus, get your motorcycle to service if the colour of engine oil retains its golden or amber colouration. 


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Why does my oil turn black so fast?

As we have mentioned earlier, blackening of engine is normal. And if the process is fast, it simply indicates your motorcycle is severely accessed. As more heating, more functioning of engine, more fuel combustion leads to colour transition of motor oil. 


So, the more you access your motorcycle, the quicker the oil is expected to change colour. 


It is important to mention that, in the case of diesel oil in an engine, the oil will always look blackish and barely retains its golden colour. This is because of the leftover residues of the old oil. The newly poured oil retains the old oil contaminants and discolours itself. 

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Does synthetic engine oil turn black?

Yes, synthetic oil turns black over time. Alike conventional engine oil, the sludge accumulation, metal and contaminants tends to darken the engine oil hue. 


Pure Synthetic engine oils are mostly clear in colour. However, it is made to be colour by adding dyes, or other additives. However, irrespective of engine oil selection, the colour transforms on use. 



Engine oil is meant for smooth functioning of the internal motor parts. It acts as a lubricant and provides smooth engine functionality. As you use your motorcycle, dust particles, incomplete combustion carbon particles accumulate and darken the engine oil colour. 


This is not harmful for your motorcycle. So, no need to worry about the colour. Instead be sincere to change it at intervals for smooth and easy riding experiences. Also it is extremely important to choose the right grade of engine oil for your motorcycle. 


To know more, refer to,  How to select engine oil grade for your motorcycle?


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