I have a 2013 mazda 3 with ~90k miles on it. It's having some transmission issues (slow shift from certain gears, intermittent whining, hard shifts). It's been doing the slow shifts for like 50k miles, but I never thought anything of it until now when the other problems have arisen. No slipping or anything else.

It's a 5-speed auto tranny and the transmission fluid hasn't been changed to date. I went to the dealer recently about this problem. They said to flush the fluid and I got the vibe they were not being entirely honest with me. "The internet" and other repair shops in the area said that's a bad idea.

Is it more cost effective to repair it now or wait for the problem to actually not allow me to move my car so as to get more miles out of the car before a costly repair?

Additionally, what are some things that can happen if a transmission were to do something undesirable whilst driving?

  • Do you cross any railroad tracks anywhere? Because A LOT things might happen when you mess up your gearbox...
    – Mark
    Apr 23, 2019 at 6:52
  • I guess you haven't yet been in the situation where you "can't move your car" while driving somewhere at night, and you can't even get a cellphone signal...
    – alephzero
    Apr 23, 2019 at 9:10
  • 1
    Paulster has pretty much said all I wanted to say about this, but what do you hope to achieve by waiting "so as to get more miles before a costly repair"? So you can extend the service interval before doing your next "costly repair"? This isn't a regular maintenance item. If the car never breaks again, then one-time fixes last forever therefore having "infinite value", and logic would suggest that you do them as soon as possible. Apr 23, 2019 at 13:23
  • @Kitsunemimi That is a very good point.
    – Joe B
    Apr 23, 2019 at 18:05

2 Answers 2


You should fix this, it's important for safety. Your transmission could slip out of gear at a critical time.

A transmission fluid problem could very well be the issue behind slow shifts and the other things you describe:

  • Low fluid
  • Old fluid: fluid degrades over time, becoming less effective. The useful life of ATF is variable but generally about 35-55k miles is my experience. Your owners manual should say. Some manufacturers have "lifetime" fluid transmissions, where they say you never have to have it changed. That's a great selling point but in practice is a bunch of hooey, it's going to need changing at some point

The first thing I would check is the ATF level using Mazda's recommended practice, which is usually with the car running and after a drive. It is probably low and nasty looking, in which case a fluid change is the way to go. I'd look for a reputable independent transmission shop to do it though - dealers are generally very expensive for no better service.

  • This is really good advice to follow here. I had my transmission go out quite suddenly when driving in a highway and I almost got stuck in the middle of a busy, fast moving highway. Not an experience I'd want to repeat
    – Techlord
    Apr 23, 2019 at 21:02

While the answer GdD gave is good, I will give you a different spin as to why you need to get it fixed now, rather than later.

The big issue you have is, if you have a small problem now, like just needing a fluid change, it's a small cost (think: $). Much smaller than if you wait until the transmission breaks down, at which point you're most likely going to need a complete transmission rebuild (think: $$$$).

If you take care of the small stuff now, it will not become big stuff later. Also, as Solar Mike and alephzero were alluding to in the comments, you can take care of it now on your time, or you can wait until later when the timing might not be as good.

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