[&o] I just got a nice, low mile 98 A8. Naturally I changed all the fluids. The local Audi deal wanted $68 for a trans pan gasket but that's another story. This sad story is about the differential. I backed the golden beauty up on ramps in my driveway. The driveway has an inline so the rear of the diff was a little lower than the front - where the drain plug is. I popped the two plugs with help from a cheater and drained it and then realized that it wasn't going to completely drain because of the incline problem. I thought, well, I'll dump in some non-synthetic 75-140 and drive it for a while, drain it again, and fill it with some synthetic. That'll give it little flush, I thought. This is what I tell myself. This is my rationalization for doing this really stupid thing. I drive it in town for a while and then head out on the interstate. Sunday morning, 30 degrees, cold wind, 75 mph, 75-140 in the diff. Lurch, grind, bad noises. Does anyone please have a good differential for a reasonable price? I'm told there is a three digit code on the diff. Can anyone tell me if it is critical that I use a 98 with that same code? Since I'm changing out the whole thing, couldn't I put one in from an adjacent year? Steve. 712-382-1017 (H) or swartout@***.net

 

It's called diff chatter. Change the fluid with the proper stuff & see if it goes away.

There is NO NEED TO FLUSH THE DIFF's! NEVER put in the wrong weight fluid.