paraffin wax, im a strong beleiver that works the best for a few good reasons.
-its a lubricant, Good for initinal start-up and break in
- makes a water-tight seal of the crankcase, easy to blast all the shavings out with a water hose
- creates a good smell of victory when you start up.
- holds the con rod steady.
-removes carbon biuld ups
basically drop the motor and get the crankcase exposed(15 min)
fill it full of wax by melting it in, port-match, blast it out with water, heat up the case facing down, and turn the flywheel until you can get a full rotation (this also helps clear any shavings left behind) then bolt it all together a start it up, any wax left behind will vaporize and exit as a vapor.