My 1864 has 680 hrs on it.I changed oil two times a year. I cut 1 acre,but this winter setting in the garage,it has a drip on the floor. I clean it up and run it for 15 min. no leak until maybe 2-4 hrs under rear motor mount right side.I think it is the seal on flywheel side.The last three years,I've always use Mobil 1 100% syn. oil.Could that cause the seal to leak and would going back to regular oil help stop the leak.I just bought a zero turn,and would like to sell my 1864,but I would like to have the oil leak fixed first.THX