How often should the gearbox oil be changed on a 1150GS, or shouldn't it be changed at all, I suppose this goes for the final drive oil also. Many thanks Watchman
According to BMW it should be every 2 years, and the final drive is every 25,000 miles or 2 years.
But if you've been fording you will need to change the final drive oil more often
I use Halfords API Grade GL5 hypoid gear oil and change both the gearbox oil and rear drive oil at 6000 mile intervals (in accordance with the BMW handbook). Like stated previously, takes little time.
Once a year is fine unless you get water into the system. (consider that a car might have it done every 4 years)
Same for the rear drive.
I use straight 90 as recommended by my owner's manual. The rear wheel drive gets the same with a mixture of 5% Dow Corning M Gear additive (moly)...since both my 03 and 04 GS Adventures came factory filled with a moly additive.