Q: The automatic transmission in my 2000 Nissan Altima has started to shift poorly, and I am getting all kinds of contradictory advice on what to do. A local shop says they can fix it for $2,500. A friend suggests I first try a $129 transmission fluid service that will drain and refill the transmission. Another friend says only a transmission flush will do, while yet another friend who has just had transmission troubles has warned me that any fluid service will ruin a transmission as old as mine. How do I make sense of this? The car has gone 185,000 miles.
A: If you plan on keeping your car for many more miles and, aside from the shifting issue, it is in good condition, it might make sense to undertake a $2,500 transmission repair. Still, it is tempting to see if a $129 fluid service might resolve the problem.
Draining the transmission will change only about half its fluid. A flush will remove and replace all the old fluid, which is a good idea if the fluid looks dirty or has an acrid burnt odor. Either of these fluid services has sometimes resolved poor shifts, though usually in transmissions with fewer miles than yours.
As for reports of complete transmission failure after a fluid service, this problem almost always occurs in transmissions, such as yours, that were acting up before the fluid was changed. These transmissions might have been doomed regardless of which measures were taken.
You do have another option: Your mechanic might be able to locate a reliable used transmission at a salvage yard, which could significantly cut the cost of this repair. Just make sure that it comes with a guarantee from the repair shop covering parts and labor.