Olleyjp
If it's of any help owners handbook says gearbox is permanently sealed whilst for rear axle use a 80W-140 or 75W-140 synthetic of the highest grade. At last service I put in Castrol SAF XJ75-140, that you can buy from a BMW dealer.
With regard to the sealed gearbox, I haven't decided what to make of this yet. It's true that on many cars these days there is no interval quoted for changing gearbox oil. Can't say I'm comfortable with this but since my S1 has only done 45k km I'm not worried for time being. Views?
Cheers
