well, still won't do anything
The only condition I've seen helped with the top end treatment (Oil, Seafoam, Mystery oil etc)
was an engine with carbon fouled rings, that had been parked. It had a lot of blow-by and using
the seafoam on it got the compression back and freed up the oil rings. A buddy of mine that owns a wrecking yard
used Marvel oil in the cylinders and lets them soak for a day or two when he's prepping a motor to be sold that's been sitting.
You don't have to run the motor, just take the plugs out and and dump the Marvel in , about 1/4 cup each hole.
Let it sit with the plugs in for a week and then spin it with the plugs out to expel the oil. then fresh plugs, wires
and start er up. will smoke a field out till it gets warm. If you pull enough yard motors apart you find a lot with
the pistons corroded and the rings froze in them..