oil residue

I know this an older thread . I have the same set up no turbo. Check your crank pressure mine was high and pushing seals out with the oil. Rotax has a procedure to check it. The 915 has 2 return lines. 

I ended up it finding a crack in the crack case that was spitting the oil out. I wonder how much strain the extra HP has on the engine parts? It was the old case so hoping the new case solves my problems.

Di you ever find your leak?