DIY E90 Rear differential oil change
14mm Hex - 1/2" drive
1/2" drive Ratchet
Low profile floor jack
Drive the car around for a while to warm up the rear diff oil.
Then lift the car and make it level.
Remove the drain bolt and insert the transfer pump into the differential and remove the old oil - real nasty, dirty smelling stuff.
Wipe everything down and insert the intake side of th4 pump into the new bottles of oil and the release portion into the differential. Begin pumping until new oil starts overflowing from the drain hole. That is why the car needs to be level.
Wipe everything down again and screw the drain plug back on.