Oil in Left side crankcase

[paperslammer]

But what if it looks like:

!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Mike Mullins]

looks like someone already tried cutting a slot for a regular screwdriver on the pictured screwhead. There is an old time muzzleloading gunsmith trick and this really works: apply heat to the area and then apply beeswax to the screwhead. do this procedure several times. Then try backing the screw out. The wax will penetrate and loosen the screw often times. It works. I'd suggest the purchase of an impact driver also. Very useful tool.
Mikeyrx