I'm currently driving my M3 Evo about once every two weeks. And when I first drive it out of the garage, this is on the floor every time: Now a little history about the car. When I first got it (about 6 years ago), it was leaking from all 3 diff seals. At the time I didnt know how to fix that myself, so I took it to a well reputed garage near Southampton, who dropped the diff and replaced the seals. About a week later I started getting this small black puddle under the car after longer drives. I took it back to the same place, and they told me that it was now leaking from where the propshaft CV joint meets the diff input flange. They took it all apart, cleaned it up, applied RTV and out it back together (sounds like they didn't seal it properly first time they dropped it, but nevermind). There was still a small 'spray' leak after that, but no drips so I was happy. Roll on another 5 years and one of the diff seals had started to leak again, so I dropped the diff myself and replace all 3. I put it all back together with a new propshaft to diff flange seal, and now I am getting this same leak again. I have crawled under and confirmed it is NOT leaking from any of the 3 diff seals. It is dripping from the metal heatshield that goes under the proposal CV joint, which means it can only be coming from that CV joint to diff flange join. Now the obvious answer is that I didn't correctly seal that joint, but I have some questions: 1) Should diff oil be leaking down the input shaft splines and into the diff input flange? I.e. is it normal for that CV joint to be full of diff oil and not just grease? I actually applied some thread sealant on the input shaft splines and nut when reassembling the diff to try to stop this, but it didn't seem to stop it. 2) if not, what could be wrong with my diff that is allowing oil to travel into that front CV joint when it shouldn't? 3) If that IS normal, has anyone got any tips on how to seal that propshaft CV to diff input flange joint? I assume just lots of well applied RTV?