I was told (a long time ago) that with the manifold reversed on the older 912's, the Rotax oil filter would not fit. As a result, I've never used one. I'm willing to try now that they have apparently solved the drain back issue. But, will it fit or is it too long and will it therefore hit the exhaust header? There's not much space there.the newer Rotax oil filters have solved this problem with an anti drain back valve