Seafoam....
 

I have been getting it at part source

^^^ x 2. Never heard of it before but I'm gonna try it!

Cool.Gonna get some when for when the GT comes out in spring.

I leave it in the crankcase for about 1000 k before scheduled oil change to dissolve sludge and varnish but it has never been done before you may want to do it twice so it doesnt comprise the filter due to loosened chunks of crap... And when sucking it into a vacuum line the engine will want to stall so rev the motor til you see the massive smokeshow that will inevitably come from the tailpipe then shut it off.... Leave it for about half an hour then take er out for a high revving spin to get all the crap you just dissolved ... When you do the vacuum line be sure to have the engine warm so the carbon is more likely to dissolve... It will smooth out idle cleans all inside oil passages... If its an older engine you will notice a difference