Mercury Outboards Leaking Oil

[crosswire]

I have had three Mercury outboards, 3.5 hp, 4.0 hp, and 9.9 hp, and have had oil leak problems with all of them when they are laid down for transportation. Yes, I have read the note about making sure the tiller handle is up and have done so. However, after about two days of laying on a side, the crankcase has drained into the truck. The motors were all new at the time with very low hours.

Is there a way to prevent this leak other than to use another brand of outboard or go back to 2cy?