The brief
Mr Amit's 318i was leaving oil stains on the floor wherever he parked it, so he brought it in to find where it was coming from. Oil on the ground means a leak that's worth sealing before the level drops far enough to be an engine problem. The flywheel sits between the engine and the gearbox, on the back of the crankshaft, and there's an oil seal there, the rear main or flywheel seal, that keeps engine oil in at that join. Over the years that seal hardens and lets oil weep out the back of the engine, where it runs down and drips. Reaching it means the gearbox has to come down, since it's sandwiched in there with the torque converter, and a hardened seal doesn't reseal, so it gets replaced properly.
The diagnosis
The check traced the oil stains to the flywheel oil seal, leaking at the back of the engine where the flywheel connects between the torque converter and the gearbox, which is the drips on the floor. The rest of the engine and gearbox were sound, just the seal gone with age. That's a flywheel oil seal replacement, which means dropping the gearbox to get at it, rather than chasing a weep that only spreads.
The work
The gearbox was dismantled and dropped down to reach the flywheel area, the badly worn flywheel oil seal removed and a new genuine BMW-spec seal fitted, the mating surfaces cleaned. Everything was reassembled and torqued to the manual figures, the oil level checked and topped, and the area cleaned of old oil so any future weep shows up. A road test and a check on the lift confirmed the engine and gearbox dry, no drips, the level holding, and no warning lights.
The outcome
No oil stains on the floor, the engine dry, the level holding between checks, and no warning lights. Mr Amit got the 318i back sealed up. The flywheel seal only weeps more the longer it runs, and getting at it means the gearbox out anyway, so doing it properly once was the right call.
