I've got an oil leak in my 04' Rx8 it's pretty substantial and its pooling right near the M of the Mazda stamp and running down the side of the engine. I've already had the plenum off and check the lines and seals, thought I found the issue in the seal of the oil filler neck but once I got it all back together the leak remained. Has anyone experienced a leak in this area? Any ideas what it could be?

 

If it is seeping out of the joint by the M.........It likely is an oil gallery leak...either from crack in the plate, or from a failing o-ring in the housing. Neither are good news. They both require a rebuild to fix, and one requires a rebuild plus a new plate...either away there isn't likely a lot of good news there

Clean it up really good to see where it is coming from

Are you sure it isn't dripping down there from the intake area above?