The brief
The 216i had been smelling burnt after motorway runs, and it had finally tripped the oil pressure warning light on the dash. The owner pulled over, opened the bay, and saw a fresh ring of oil around the cooler housing.
That last decision was the right one: he had the car towed in rather than driving it the rest of the way. An oil pressure warning is not a 'finish your journey' light. It means the engine may not be getting the oil film it needs on its bearings, and driving on it is how a leak becomes a rebuild. The burnt smell after motorway runs had been the early warning, oil weeping onto hot parts and burning off, and the warning light was the system telling him it had gone far enough.
The diagnosis
On the lift, the leak point was traced cleanly to the oil cooler gasket. The gasket had hardened and lost its sealing edge along one side, which is what these do over time and heat. The cooler itself was clean, no internal damage, so it could be reused; it was the gasket that had failed.
With the oil pressure already low enough to trip the warning, the right move was to replace the gasket and also give the rest of the oil system a careful look before refilling, to make sure the low pressure had not done any harm and that there was nothing else weeping. Everything else checked out.
The work
Removed the cooler, cleaned both mating surfaces, the cooler face and the block, back to bare metal, because any leftover hardened gasket material stops the new seal sitting flat. Inspected the cooler internals: clean.
Fitted a new BMW-spec gasket with new bolts, retorqued in the proper pattern so the cooler pulls down evenly. Refilled with fresh oil.
Then verified oil pressure on the gauge before the car went out, because the whole point of this job is the pressure, and a gasket fix you do not confirm on the gauge is a gasket fix you have not finished.
The outcome
Oil pressure back in spec. No warning light. No traces around the cooler. No smell after a road test.
The 216i went home with the leak closed off and the oil system holding the way it should. For the owner, the practical win is an engine that is being run with proper oil pressure again, and a problem fixed before the low-pressure running could cost more than a gasket.
Towing it in rather than driving on the warning light was the move that kept this to a gasket and a refill.