Mineral

I'd use it to top off between changes and throw in a quart or two in with your regular changes unless someone else needs the oil.
 
Like Mannan says, just use it in conjunction with your regular oil. Won't hurt a thing.
 
I still have oil in IO-360 Lyc from when it was shipped, getting ready to start up. Whats the rec oil for break in? Mineral Oil Like what Aeroshell ???
 
The oil you want is AEROSHELL 100.

When you are done with that use either the Aeroshell W100 Plus or the Aeroshell W 15W-50. My preference is the 15-50 :)
 
Like Mannan says, just use it in conjunction with your regular oil. Won't hurt a thing.

Do you need to worry about adding Lycoming LW 16702 antiwear additive since Mineral Oil does not have it formulated in?