My new to me MkV mini with a 1275 lump has a dipstick that just sits in a hole in the engine casing. Not support tube and the whole stick just seems to freely spin and can move in/out the hole with no effort. I'm thinking this is a possible cause of oil leak on front of tranny casing and around the oil filter bracket.
Seems the rubber grommet on the dipstick is not doing any sealing...maybe worn away? Crankcase pressure must surely force oil up and out there and potentially let water/dirt in???
Decided to try fitting an o-ring....but needed to grind a groove around the rubber grommet to better secure the o-ring. Used my dremel with a tiny ball-head cutter bit and just slowly made the groove while turning the stick. Got the o-ring well seated with just a bit more outside diameter than the grommet material had. Found this needs a small push to seat the stick...and now it holds quite well. Decided to make a second groove and fit two o-rings. Checked that the stick does indeed go fully down into place....so level reading should not be affected.
My first Mini Mod 
Hoping this reduces the oil drip.
