It's like top engine cleaner.. Ford sells a more powerful version of it under the motorcraft name
I used to use it on my old pontiac all the time, just to see the reaction of people as you drive by with a big plume of smoke pouring out the exhaust
I didn't notice much difference with it, but the smoke cloud grew less and less each time I used it.. about once a month.. way too often
only thing I noticed is the oil right afterwards was much thinner than it had been previously, had lots of crap in it.. so you might want to wait til you have to do an oil change, then do it, then change the oil...
Like I said I didn't notice any difference, but it didn't hurt anything either.. engine had 140 some thousand on it, and I still see the lady I sold it to driving around today..
