Hi Robbie Most unlikely that the crankcase will split as there are other more accessible places to exit the engine. My finding, was that the oils were pumped to the top of the caseing and spit out into the filter and down the breather pipe. The aftermarket seal was previously fitted in a rebuild but unfortunately lasted only a couple of hours engine time. We promptly ordered a new right hand crank seal from Honda to cure our oil problem, it only takes about an hour to change, that was 25 hours of riding time ago. The oil has remained separate since,so the message is! dont use aftermarket crank seals.