If you have a stuck compression ring, you can use Berryman B-12 Chemtool Fuel System Cleaner (part #0116) for combustion chamber cleaning if want to perform a cylinder soak. That is accomplished by pulling the plugs, putting 0116 in each cylinder (or at least the cylinder you know to be a problem), letting the product dissolve the carbon, and then removing the mixture from the cylinder(s). If you have a V-configured motor, then it may take nearly a full bottle of 0116 per cylinder to ensure that you cover the entire compression ring, especially if that ring is stuck and allows some of the B-12 Chemtool to migrate toward or into the crankcase. However, if you don’t mind soaking one side at a time, you may be able to jack up one side of the vehicle to flatten that bank of cylinders a bit and thereby cut the amount of product required. You can also buy Berryman B-12 Chemtool Fuel System Cleaner in a 1-gallon size. That part number is 0101.