I use it in the oil just before I change oil, it's like a 5 weight, thinner, to clean the black soot out of the engine. We used to pour aft down the carb to knock the carbon off the heads and pistons, at 2000 rpm. I was told to put in the fuel to clean injectors, gas or diesel. I'll put some aft in a little diesel to see if it turns red. I have been checked by the DOT in my pickup, the cop said it would pick up any dye in the fuel not additives, they're just making sure you're paying the taxes, $10,000 fine. Put some dirty greasy-grime on your hands then put some aft on, it will clean off that grime quickly. I know it's less lubricating, but to clean anything it has to cut through what you're cleaning. Soap isn't used to clean your hands, it's used to make the water molecules smaller than the dirt to float off your hands, so I guess this is what the aft does.
In my opinion, have to add that so no liability.