Saw Xqwizit, Dallas09, ImThe Devil discussing changing rear differential fluid, and transmission fluids on forum. I'm still trying to get the hang of this site, new at this. Have a 2004 A6 2.7 quatro, have had the car around 2 yrs. and it has around 106,000 miles give or take. Should I attempt to change these two items. My wife mostly drives the vehicle and she is 60. We don't do too much Nascar racing.