Yo, Joltan!
Take the spark plugs out of the engine,
Load up each cylinder with Marvelous Mystery Oil, put the plugs back in
the engine, let it soak for about a week.
Pull the plugs out, and crank it a couple of turns, to avoid hydraulic
lock, put the plugs back in, and see what happens.
IF, and I mean IF, you have a stuck ring, this will 9 times out of ten
free them up.
However, how have you determined that you have a stuck ring, and not
just a good old fashioned worn out cylinders?
Nothing you can do, with a "miracle in a can" will replace worn out,
gone bye, bye, metal, not even Marvelous Mystery Oil.
You have of course, taken a compression reading on all the
holes---right?

Later,

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Terry 85 GL