When should I change the transmission oil in my Toyota Yaris?

We bought a Toyota Yaris automatic (2001 model) with 22,500 miles on the clock that had been serviced regularly until last year. It's now done another 8000 miles :my question is when is it best to change the automatic transmission fluid?
This is a robust four-speed torque converter autobox with the benefit of a dipstick, which is clipped in place. If you extract it and have a look at the fluid on the end that will tell you if it needs changing or not. If it's pink, it's fine. If it's red, even darkish red, it's still okay. If it's black it needs changing.
Answered by Honest John on

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