I have 200k miles on my Sienna. The last transmission service was at 110k miles. The tranny has no issues. Would there be any reason not to service it now?
It’s overdue for another service. Verify with your owner’s manual. Congrats on a good life out of the Sienna.
Absolutely no reason not to service it.
You should have the transmission serviced every 30K miles - “serviced” means having the pan removed & the filter changed. DO NOT let anyone flush it. As such, you are about 60K miles over due and should be on your third service since the one at 110K. Being this long past due you could get a full fluid exchange but only AFTER the filter has been changed.
This is regardless of what the owner’s manual says. Normally those service intervals should be followed. But in the case of transmission the intervals given are terrible for good mainenance.