I did mine a 200,000 shifted better less drag but have to use there transmission fluid $$$ but easy to do Posted via the PriusChat mobile app.
I recomend changing at 30,000 miles, then 90,000 then every 90,000. For a 2007 I suspect that means every 90,000 miles, as you are past the first two. DIY should be under $50, my dealer charges $110. 4 quarts of ATF WS (you use 3.5) and 2 crush washers at the parts counter.
Read Bob Wilson's and Prof Eddenberg's ATF-WS oil analysis. They determined some aggressive intervals, based on sound oil analysis: 30K miles, then every 60K miles. Transaxle oil, recent analysis | PriusChat Read post #473, to see the benefits of a strong transaxle drain plug and early dran/fill, as recommended by Bob Wilson. ATF fluid changes ARE Required. | Page 24 | PriusChat
