And if so, what do you use? I've been using orange cleaner or Purple Power but I haven't done mine in a year or more. It's a 2007 silverado classic and although it doesn't consume a significant amount of oil between changes, I see significant crud on the front and sides of the engine. I bought a can of Gunk and plan to clean it in the morning before I drive anywhere. My girlfriend's car is a 2014 Pathfinder and the so-called organic cleaners work fine under the hood, because her only issue at this point is road dust. What do you folks do?