BG Products, part no 109. It's an additive. Basically, you get the engine to operating temp - pour this stuff in the top of the motor. I pulled the PTO throttle out to about 1500 rpm and let it run for 10 mins. I changed the oil filter - used a Fram, what ever was cheap - and ran it another 10 mins, then changed the oil. To preface this, I used Rislone in the 2 previous oil changes, which were only 800 miles apart to loosen up some of the crud in the engine.
I am not a big proponent of additives - Sea Foam and the like, but this BG 109 definately worked as advertised. It is billed as a Compression Performance Restoration, for what thats worth. I am curious to see how the oil looks at the next change - it was thick and black after running the treatment through. That is why I changed the filter - I didn't want the the filter backing up, going into bypass and making things worse...
So, that is my experience.