Ok.....here is what I know to be correct when reading spark plugs: Gray (or grey) to light brown is good. White represents a condition that is too lean. Black represets a condition that is too rich. Attached are the plugs just changed from my 2007 Heritage with 35000+ miles. I have never run a fueler. I like that they look the same for each cylinder. Agree?? I'm interested in you opinion.