Every 12 monthes ! your poor Mini Ryan

If it is an auto then dependant on the year 20/50 for earlier models 10W40 for later models 90 onwards, is a starting point and change every 3 months or 3000 miles regardless, as any moisture in the system destroys the clutch plates within, and there are 6 clutch plates, also any petrol contaminates destroy the rubber seals
