I tried searching and believe it or not I couldn't find a thread on this - although I know it must get asked a lot For a new car with a new filter and new oil... why does the oil generally turn black by 3K miles. I realize some dirt and combustion byproducts get introduced... but black??? I could understand if the color went from amber to light brown but I am surprised just how dirty oil gets. Thanks for your help P.S. Can someone point me to threads that discuss this?