Four problems related to engine oil leaking have been reported for the 2006 BMW 3 Series. The most recently reported issues are listed below.
Oil keep leaking out of training. It was fixed twice so far. Back brake line keeps breaking when you drive in snow.
Broken cylinder head bolts at the front timing cover. Symptom was oil leak at timing cover. Upon inspection, the heads of 4 bolts had sheared off and 3 bolt heads had dropped through the timing chain housing and ended up in the oil pan. First, head bolts should not fail. Second, the sheared bolt heads pass through the timing chain housing and could interfere with the timing chain and cause immediate engine failure.
Front two valve cover bolts sheered off causing oil to leak directly on the exhaust.
My car started having a massive oil leak at around 79,000 miles. The motor seals started to fail once the car had about 70,000 miles on it. The general consensus is that the motor seals are very common to prematurely fail. The bolts that hold the motor together started to break at around 80,000 miles.