If the rings are rusted to the pistons, the Kroil will usually free them up and allow the compression pressure to get behind the ring and help it seal. I like to recycle it several times by draining the Kroil from the crankcase and pouring it back through the spark plug holes. It runs right through rust and ends up in the bottom of the engine.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!