HOW OFTEN SHOULD I CHANGE TRANSMISSION FLUID?

Here’s an honest reply: with over 227,000 miles on your RAV4 and since your transmission is working well, don’t worry about things. As long as your transmission fluid doesn’t have a burnt odor or doesn’t feel gritty to the touch, there’s nothing to worry about. Just leave things as they are. Your transmission is quite happy with the fluid and vice versa so there’s no reason to change. Sometimes, honestly, the documents that tell you to change the fluid at XXX miles for best performance are well meaning, but they aren’t right for your vehicle. Instead, you have to go with what you know. In this case, since there is nothing wrong, why change things?

Here’s what might happen if you do: since you will likely change the tranny filter at the same time, there’s a good chance that a stray deposit that it might be holding will break free and fall into the transmission, unknowingly. That debris might then slip through when you refill the transmission and become lodge somewhere it shouldn’t be. It might be on a sensor probe or in one of the many galleries in the valve body, plugging it up. The probe might go from good to bad and start a chain of events that could end up with you having to put in a rebuilt transmission.

There’s an old poem that comes from somewhere (it could be part of Shakespeare or some other famous author of old) that reads: “for want of a shoe….)”. By the time the poem is done, the good king has lost the war and everything’s a mess. In the case of your transmission (the good king here), just changing the fluid introduces a whole new range of “shoes” into the picture that could end up causing you to lose the battle.