Oil leak e46

Could be turbo leaking oil worth a look anyway if coming from there

What engine is it? Most of the petrols burn oil after 100,000 miles due to the use of low tension piston rings in an attempt by BMW to reduce fuel consumption (as much as a litre every 600 miles), are you sure it isn't just that?

Those engines can burn oil to beat the band, valve stem seals are a noted trouble spot with them. They do burn oil courtesy of the low tension piston rings.

Are you sure it's not just burning oil? Unless the oil burning is excessive, they don't usually show any signs of any sort of smoke, a bit of white smoke the odd time maybe but it's usually steam when they haven't been driven on for a while.

Another thing to check is the type of oil used. You should use good quality fully synthetic LL01 or LL04 spec oil from a reputable brand such as Petronas, Mobil 1 or Liqui Moly and not the cheapest thing in a petrol station. Also make sure to use 5W40 to try and reduce the oil consumption, 5W40 is the thickest oil approved by BMW for these engines so that's what I would use.