BMW E90 328i (N52): Oil Filter Housing Gasket Leak

Symptom: Oil seeping from the oil filter housing where it meets the engine. Oil runs down the block, often toward the exhaust or starter area, leaving a burnt-oil smell after driving. The oil level may drop slowly between changes.

Vehicle focus: E90/E91/E92/E93 328i and related N52 engines (mid-2000s–early 2010s). Extremely common leak; DIY threads are abundant.

Likely causes (ranked)

1. Failed oil filter housing gasket (profile gasket flattens and weeps) — Primary cause. OEM-style gasket (commonly referenced as BMW part 11427537293 in DIY threads).
2. Oil filter cap O-ring — Can leak at the top of the housing; check before or while you are in there.
3. Related plastic coolant flange / thermostat housing area — Not the oil leak itself, but DIY guides often recommend inspecting/upgrading brittle coolant plastics while coolant is partially drained for access.
4. Other N52 leaks misidentified — Valve cover gasket, oil pan, etc. Confirm the wet spot starts at the filter housing joint.

Rough cost range

DIY or shop?

• Popular DIY for owners with basic tools (E10/E-Torx or 8mm access on the awkward rear bolt, torque care, coolant partial drain).
• Shop if you are uncomfortable bleeding coolant or risk rounding the hard-to-reach housing bolt.

Useful steps

1. Clean the area, drive, and confirm fresh oil at the housing-to-head joint.
2. Drain enough coolant so opening the housing does not make a huge mess (guides often remove ~2 liters / half gallon).
3. Remove the three housing bolts (the rear one under the intake runners is the painful one — ratcheting wrench helps).
4. Replace the one-time profile gasket; clean both aluminum surfaces carefully (plastic scraper preferred).
5. Refill/bleed coolant properly; check for oil and coolant leaks after a heat cycle.
6. Many owners time this with an oil change so any spilled oil is replaced clean.

Safety / mechanic note

Burning oil on a hot exhaust is a fire and smoke concern — fix leaks promptly. Coolant work requires a proper bleed to avoid air pockets and overheating. If oil is mixing with coolant (milky oil or oily coolant), that is a different failure path — stop and have a BMW tech diagnose before assuming it is “just the filter housing gasket.”