Dirty-coloured oil doesn't mean oil is dirty

It is a common misconception that an oil’s color is an indication of how “dirty” it is. This is not true. It is often a common tactic used at quick lubes and service centers; the technician pulls the dipstick and wipes it on a white shop cloth and shows the customer how “black and dirty” it is. Any oil will turn black after a short period of use. Some oils may stay “clean” looking longer than others, but eventually they all will turn black. This is perfectly normal.

When someone tells me how “clean” their oil is because they have pulled the dipstick and it looks clean I always tell them that it will eventually turn black. They also tell me when they pull the dipstick and it has becomes black and “dirty” it will require changing. The physical looks don't don't reflect the truth, is the chemistry that counts thus the Lubrication Ability and Contamination Level.