My spare 235 was locked up with two cylinders that would not drain down oil from the top as the head was off.This sat for about 4 years in the corner of the garage.I ended up taking it apart and pounding on the pistons with a piece of wood .i tried atf mystry oil fuel oil and .I think that heat is a good idea .the two pistons that were stuck were all gummed up and the rings stuck but a good candidate for a rebuild.
