I’d noticed some transmission noise in my 2012 Scion iQ over the last few months when the transmission would get, so I finally got around to changing the fluid a couple of weeks ago. Some Googling beforehand showed that while I could figure out how to do it, no one had thoroughly documented the process, and because the car has a “filled for life” transmission, the materials that Toyota publishes about this process make no mention at all of how the process is supposed to be done. Unscientifically, it seems like the change interval for the fluid in this transmission, at least in hot climates like central Texas, should be maybe 30,000 or 35,000 miles, or maybe five years. My car had about 40,000 miles on it when it started to make some noise, and while I gather the noise is mostly benign, it’s disconcerting, and suggests that the fluid unsurprisingly does have a finite life span. In other CVT-equipped models, Toyota does specify a change interval, which is around 40,000 miles, or so I’ve read.
Anyway, I figured the process for changing the fluid out, based on past experience and what the shop manual does say, and made a video.
I mention it in the video, but I did this in basically the hardest possible way, and it turned out that it isn’t actually necessary to remove the pan like I did. When I did remove the pan, I discovered that there is in fact what appears to be a filter, or at least a strainer, inside there, but my best attempts to find a replacement filter have come up empty; it appears that the filter isn’t meant to be replaced any more than the fluid is. Luckily, at least the fluids and gaskets needed to change it are available. I was able to get the job done successfully, and the gear noise is gone now.