I just acquired a 2007 Toyota Prius with135,000 miles on it. I am going through the process of bonding with it now. In the Navy they call this process sea trials. I just changed the transmission/ transaxle fluid. Doing a brief search on the Internet I could not find a consensus on when the transaxle fluid should be changed. I couldn't even find a consensus on what type of transmission/transaxle is in a Prius. There are posts out there indicating that if you do not change the fluid that your transmission may begin to slip. Unless I'm completely living in the dark the Toyota transaxle has no plates to slip. It’s not an automatic transmission. Having said that and having just changed the fluid I thought I would share the oil analysis of a transaxle with 135,000 miles on it with the community. (see attached PDF) It is obvious that that it was past due. I have the complete service record for this vehicle and there is no indication that the fluid has ever been changed. However, there is no way to know that for sure. I plan to sample and have an oil analysis done on the fluid in about 10,000 more miles.
Yikes, those silicon and aluminum levels are scary....good job changing it out! I just change all my vehicles' transmission fluid every 5-years or 50,000 miles. Some Toyota's (like my Tundra) also have an internal transmission filter but since I change the fluid so often I don't bother dropping the pan to change it out. My engine oils get changed out every 6-month or 5,000 miles...too many who do just 10,000 mile changes are reporting head gasket issues....not worth the risk. I follow the maintenance advice on the YouTuber, The Car Care Nut. He's been a Master Toyota tech for over 10-years and just went over 1 million subs on his channel....great guy! (Ahmed)
A couple of things. I think we do readers of this forum a disservice and calling the Prius transaxle a transmission. It makes things confusing because it is not a transmission in the most common sense of the word. Sure, it transmits the hybrids energy to the ground but it's not a 4 speed or a traditional automatic transmission. For the life of me I have been unable to find Toyota’s recommendation for changing the fluid. Surely, they don't think the fluid lasts forever. Especially in a vehicle that routinely goes many hundreds of thousands of miles. The oil analysis I had done makes it apparent at least to me that the oil/fluid needs to be changed at a regular interval. What that is for my car and the conditions it is driven in remains to be seen. The official Toyota recommended service chart that I have only makes this mention. 2007 Prius 30,000 Miles - 36 Months Inspect the following: Transmission fluid or oil Additional Maintenance Items for Special Operating Conditions: Driving While Towing Replace front differential oil (manual transmission only) Replace manual transmission oil The little Prius has no front differential or manual transmission. Why it's listed in service recommendations for a Prius I have no idea. I have been accused and may even be guilty of being able to look straight at something and not see it. So, if someone out there has seen Toyota's recommendations I would be curious to see it. But for my part I will rely on the oil analysis to guide me on when to change the fluid. I will post an update in about 10,000 miles.
This is similar to the transmission in my Suzuki burgman a fancy belt running across two sheaths that move in and out and essentially have a continuously variable gear ratio but the fluid inside of them is still getting slung around and parts of the belt and sheaves and what other ever metal in there is wearing down It has to it's just the nature of the beast some people say this transmission oil is permanent yeah permanent for them because they're out of the vehicle at 150,000 mi it was permanent but the somebody who's going to own the car like forever three to five years is a good thing I don't think in that timeline you're going to see too much too scary and probably not much is going to happen considering I've seen these exact same vehicles least the generation twos with 300,000 in the fluid I'm taking out is original and I'm sure the levels of everything are scary is all get out so I don't look flush them out new fluid sheets running done.
Yep it's called a CVT but it's not really a CVT...I think the official Toyota term is E-CVT. I've owned a Prus since 2017 and don't recall a single person in here talking about a transmission going out or needing to be replaced. (Some had abnormal shifting but fluid change fixed it for them.) Not much maintenance beside oil and coolant besides cleaning out the MAF sensor (just remove and spray) and Throttle Body. (Just clean out the butterfly flapper and area with a rag and special Throttle Body cleaner) My AWD Prius has an electric motor in the back with drain/fill plugs like with a differential and that thing only took 1.4 Qts of Toyota WS when I did it last year. (I drain/fill every 25,000 miles but it was so clean I'll probably let her slide a bit more next time....maybe 60,000 miles) Easiest car EVER for the DIYer!!
