How do you change the oil in the rear axle drive housing? Does the car need to be on a lift or is this a simple drain plug deal like the transmission? Does anyone have some photos or job aid instructions.:help

Don't they have two drain plugs? pull the bottom one to drain, then put it back in, open the top one and fill until it's full.

There are pictures in my rebuild thread: LINK (http://forums.bimmerforums.com/forum/showthread.php?t=954295&page=2)
You'll need a 8mm hex key.
Folks recommend a synthetic lubricant like Redline or Mobil 1.

Use Redline Gear oil. Make sure you can remove the fill plug before you remove the drain plug. You will also need a pump to get the fluid in. It will take about 1.3 quarts of oil, you stop pumping when the oil starts to spill out the fill hole.