The car is a 1993 Audi 100 CS quattro with a ZF automatic transmission. The odometer showed 227000; past maintenance history not known.
The engine would rev a few hundred rpm on the 3-4 upshift when at operating temperature.
I changed fluid and filter; it did not help. I installed Lucas transmission fix (you know, that stuff that is as thick as STP); that did not help.
I installed 6 oz. ARX; that not only helped, it completely corrected the problem... and only after a few hundred miles! Furthermore, the upshifts, which were a bit soft (but not bad) are now very quite firm.
I drove 1300 miles, then dropped the pan and changed the filter again. Things looked very clean in there with barely a hint of fuzz on the magnet. The fluid looked like new.
I'll perform a drain and fill a couple of times just to insure that any bad stuff that may be in there is mostly gone.
Nearly 3000 miles have elapsed since I treated the tranny to ARX and it continues to run strong.
So far, this stuff has worked every time I have tried it!
