in the early days of my motoring (**** I feel old now) I ran a 2 1/4 petrol that was past its best.
slick 50'd it on an oil change.
year or so later when it started smoking and burning oil, stuck a bottle of smoke stop in it. cured it for a week or 2.
in the end I ran it for a week with the oil pressure light on due to worn bearings, and by the end of the week it was knocking and rattling, till it eventually wouldn't pull the motor, but still ran.
swapped the engine and ran it for another 2 years.
make your own mind up, I think the slick 50 helped, tho the engine was beyond repair anyway.
edit-
not used it since, and not had an issue with regular maintenance........