You should change your filter every 20,000-30,000 miles in order to assure that your automatic transmission fluid is clean and free of debris. Always check your fluid level, as low fluids can cause catastrophic transmission failure.
10-2043-009-M30
Transmission Filter Kit, with filter & pan gaskets, Auto Trans, 924/944 All (1983-89), Each [More Info]
$9.00
010-398-009-M30
Transmission Filter, Auto Trans, 924/944 All (1983-89), Each Brand: Elring Klinger [More Info]
$11.00
010-325-443
Transmission Filter Gasket, Auto Trans, 924/944 All (1983-89), Each [More Info]
$1.30
010-321-371B
Transmission Pan Gasket, Auto Trans, 924/944 All (1983-89), Each [More Info]