Doesnt it also have a lot to do with the type of enviroment that you are in?

I use Castrol 10w-40, course I havnt used anything else before. But it seems to always be the same color...course i think it is now burning oil <img src="/forums/images/graemlins/scared.gif" alt="" /> <img src="/forums/images/graemlins/confused.gif" alt="" />