If your engine is a 4 stroke, the only place you can effectively inject the after run oil is into the crankcase breather tube and not just a drop or two, you need to squirt in about a teaspoon full to be effective.
I did not note what size 4 stroke this amount applicable. Big difference in volume of case between say a FS 30 and FS 120. Can you use too much oil in the crankcase breather fitting? I happen to have a new O.S. 52 FS Picked up some 3-in-1 oil to use just may dilute with some AFT Fluid.