When it comes to maintaining your transmission system, it’s sometimes necessary to read between the lines. There is no single approach that fits all cars. For instance, the discovery of dirty transmission fluid may call for prompt replacement in one vehicle, but actually leaving the dirty fluid in place in another car with a certain pattern of maintenance!
There are other conditions at play as well, so with the kids safely preoccupied with their Christmas video games, and having already made the most important decision of the holiday (whether or not to have that second piece of pie), why not pull up a chair and review these aspects of transmission service:
For cars over 80,000 miles, here’s where the tricky part comes in to play. Let’s say you have noticed slippage or hard or erratic shifting. The question then becomes: Have you been naughty (not performed regular transmission service) or nice? If you’ve been nice, your mechanic may recommend replacing the fluid or flushing the system. However, if you have been naughty and not kept up with maintenance, the recommendation may actually be to LEAVE any dirty/gritty fluid in place. The reason is that internal transmission parts that have been worn actually do better with dirty fluid, which provides needed friction. Replacement with clean fluid in an older car can actually kick off problems with slipping.
Of course, if there has been actual damage to the transmission and this is causing the shifting symptoms, repair or replacement of the system may be necessary.
After performing diagnostic tests as well as driving the vehicle, your mechanic will recommend either replacing the transmission fluid and filter; flushing the system to completely remove contaminated fluid as well as any deposits on transmission parts; or repairing/rebuilding the transmission if there has been damage to the system. By keeping up with your regular maintenance, however, you can help to remove that third, more expensive item from the transmission service menu.