To maintain the automatic transaxle and differential fluid in good condition in 1989 and earlier models, it is key to change fluid from time to time. Also, make sure you have the proper transmission fluid and tools, a 10mm Allen wrench, as well as a drain pan. After driving the vehicle, completely drain the fluid. You can raise the vehicle, place the drain pan underneath the transaxle drain plug, and catch the fluid. Reinstall the plug, unfasten the bolts, lower the pan, and wipe the gasket surfaces. Also, install a new gasket and attach the pan. Start the engine, go through all the gears, return to p, and check the fluid level.