As many of you know, I just bought my first Prius (2012 Two) a couple of months ago. Today, I did the first real service on it by changing the transmission oil. I was not prepared for the amount of work needed under the car and it ended up taking me nearly six hours to do everything. Here are a few observations: 1. Raised vehicle on four jack stands in my garage and found that there was not enough space to work under the car. So I raised the front end again, which made the car slightly off level. 2. When removing the engine under cover, a few clips broke and the box of new ones I purchased did not fit any of the positions, so that was a total waste of money. 3. The old transmission oil was completely black. In comparison, I did transmission service on my 2006 Civic last week after 37K miles interval and the oil color was not very dark. 4. I was able to drain about 3-1/3 quarts of oil. To fill new oil, a clear vinyl tube was routed from the engine compartment down towards the transmission housing. A small funnel was attached at the top. The first half quart went in pretty fast, after which it was a slog because of trapped air inside the tube. It took me a good 30 minutes to refill. Right around 3-1/3 quarts in, the drip from the fill hole started. 5. The amount of oil that drained and refilled was less than what most of you have experienced. So I guess having the vehicle front angled up slightly does make a difference in both drain and refill. I found it hard to level the vehicle perfectly on the stands. 6. Given the drained oil was so dark, does it make sense for me to drive 5-10K and then repeat the drain and refill? I can't believe the previous owner never bothered to change the transmission oil. The vehicle was serviced regularly at Toyota of Butte, Montana, and it was in their care until 136K, so I don't know why they never serviced the transmission.
Toyota claims that ATF WS is a lifetime fluid - but I'm surprised the dealership didn't try to up-sell that. These transmission are planetary gear sets, so as long as they stay cool and something lubricates the needle bearings - they can go for a good long while. Changing the ATF every 60K to 100K actually puts you ahead of the game, since most people don't touch it. Some even argued that it was a SEALED unit, therefore unchangeable - strange how the service manual states to check it.
Which presumably (according to toyota) ends as soon as the last of the warranties on the vehicle end. Here is an excerpt from the repair manual: (a) Add transaxle fluid until the fluid level is between 0 to 10 mm (0 to 0.394 in.) from the bottom lip of the filler plug opening. Stop the vehicle on a flat road. Recheck the transaxle fluid level after driving when exchanging fluid. Insufficient or excessive amounts of transaxle fluid may be the cause of some trouble. So you are supposed to jack up the vehicle on a flat road somewhere during the test drive and check the level? Some of these directions in the repair manual are so nuts.