I had smoke out of the exhaust and oil drips on the floor at 60000 miles. I first noticed when pulling away from lights smoke coming from exhaust. Landrover dealer, very helpful, said immediately engine crankcase breather an item which Landrover revised the change period to 12000 miles, this is not commonly known and is not in the service manuals. Cost about £30 from dealers and easy to fit. Just remove air filter and you will see it. It is also fitted to the Rover 75 diesel and 2 litre BMW's. The actual problem is not the filter blocking but the spring loaded diaghram under the round section. I took mine apart ( just clips to prise open)and found this was stuck to the plastic, If not done pressure can build up and blow turbo seals, free off and spray a little with WD40 Silicone spray available from Halfords.