I purchased a 2015 RAV4 at 30,000 miles and now have just over a hundred thousand miles. I've driven the car myself and I'm a 60 year old guy who just drives normal . I've never changed the transmission fluid because it was considered a lifelong fluid in the manual. Even when the ambient temperature is warm I've noticed on the first drive of the day the transmission will shift through the first three gears and when it shifts from 3 to 4 it will flare, but I don't know if it's because the throttle pressure is light or if it's because the transmission is truly slipping. I was hoping to get some advice from somebody who's dealt with the same problem. I've seen the Car Care nuts videos claiming if you got over a hundred thousand miles on a Toyota transmission not to even change the oil so I'm not sure what to do. I was thinking maybe I need to drop the pan and take a look at how much debris there is and change the filter then add for quarts of world standard. I don't know if it would be worthwhile to change the oil and filter and try to flush the system with some seafoam additive. Any advice is appreciated.