The oil cooler sits in the V between the cylinder banks, and its seal becomes porous over the years. The leak is characteristic: there is no visible trace on the outer sides of the engine, because the oil collects in the V under the intake and drips down from there. A smaller oil puddle can therefore appear under the car, while the place of the leak cannot be found from outside. As the fault gets worse, oil can also get into the coolant, and that shows up as oily streaks in the expansion tank. It gives no fault code. The repair is expensive because the cooler can only be reached after removing the intake and the swirl flap actuator. In a specialist workshop it can run up to 2,000 euro. The fault comes up above 120,000 km. One thing is worth asking even after the repair. If the V is not cleaned out thoroughly, the remains of the old seal and the soot get into the oil circuit, and there they can ruin the bearings and the oil passages as well.