My brother's approx. 2010 Scion's oil seems to get dark rather quickly as well. I've heard that darker oil means that the oil is doing its job and keeping the engine clean by bringing the contaminants into the oil. Do you think the older Ford has a lot of particles in the engine not getting picked up by the oil, or perhaps do the new Japanese cars produce more contaminants for some reason? I'm pretty baffled by this. I've personally changed and only ever put synthetic oil in my Honda, but I've been letting Jiffy Lube put whatever they put in my Ford. Any other Asian vs. U.S. etc. oil color observations might help me know whether this is a fluke or others are experiencing the same thing. Thank you. One of my theories is that maybe Japanese cars are built tighter so they are "rubbing" more, so to speak.

1 Answer 1


It's very difficult if not impossible to compare how oil discolors in two different engines.

First, both engines would have to have the same oil in it. That way the chemical composition of the oils is the same, they have same type and amount of detergents and friction modifiers.

Second, the engines would have to be driven in exactly the same fashion. Same amount of drive time, same amount of warm up time, same amount of cool down time, etc...

Third, the oil filters would need to be exactly the same, filter element, element size, bypass valve spring tension, etc... If the filters are not the same then at least be the same manufacturer.

Finally, the wear level of the engines would have to be exactly the same. If one engine is worn more then the other the oil may discolor differently. The best comparison would be if the engines were both brand new.

With all of these variables, comparing the color of oil is almost pointless.


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