I've heard these things are notorious for leaking. Having it fail shortly after install would be nightmarish given the amount of work required to access it.
There is a tab in the block that was engineered to facilitate removal. If the seal is not inserted deep enough, and past flush, it will leave a gap and oil will leak. The seal that was in there had silicone filling this gap, but the manual does not mention doing so.
I installed a new seal until it bottomed itself on a machined stop inside the block. That's the season it's there. The seal seemed to have gone in pretty deep. I measured it to be about 3.25mm past the flange.
As an extra precaution, after installing the seal, I put a thin bead of RTV around the edge, and filled the removal tab.
