Hi, I have a Peugeot 407 1.6 HDI with 130k Miles on it - Its serviced regularly and it uses about 1/2 to 1 litre of oil every 300 + miles - It gets hot with the regeneration cycle to the cat and the fan stays on after the car has stopped for 5 minutes. No problems with the engine or turbo otherwise. I am wondering if thats using up oil, its doesn't smoke or have an oil leak. Would an oil treatment like STP or a higher grade of Oil like 5/40 help reduce oil consumption ? I have been using 5/30 normally.