My Cygnet SF2A has a 2276cc VW assembled from Great Plains kit. The engine was assembled ~2014 from parts acquired 5-7 years earlier. Currently has about 150 hours. I grounded it August 4 when it looked like I had a rear main seal issue with oil slinging out of the accessory case. Ordered a rear seal and proceeded to separate the engine from the plane. It became apparent the main seal was perfect but the face of the crank and flywheel was leaking making a mess. I have a 8 dowel crank and a fiberboard gasket that had failed. After reviewing situation I have a non o-ring flywheel. We examined options to machine in a groove but there was insufficient parent metal. Happy to report after calling Art at Great Plains they have updated the 311- 4 dowel and 312 8-dowel flywheel to include a O-ring groove. After confirming I have a O-ring compatible crank I ordered one. It is too much work to pull a engine and a new fiber gasket was just asking to do this again in 1-300 hours. REF https://www.thesamba.com/vw/forum/viewtopic.php?t=692467 I will install the new flywheel and source whatever shims I need to set the end play. If you find yourself leaking around the dowel pins review this area and consider upgrading to the O-ring solution. It is also recommended if you have a 8 dowel crank to use the larger diameter HD washer under the gland nut. I will do this also while I reassemble everything. Hope to be flying again next week I need to do my cross country and schedule my check ride! Please share your experience with sealing this end of the equation.