Question for the group - transmission oil change at 159k miles?

if you're keeping it, absolutely. no problems reported here, many have done late changes

 

It's no big deal either way. Toyota never specified a replacement interval for the ATF. They don't think it will ever need to be changed.

Some members have changed theirs and noticed... nothing other than a lighter color in the new fluid.

It should be understood that the Prius CVT is unlike all the others on the market: there are no friction parts bathed by this oil. No clutches, no drum and band assemblies, no chain and sheave stuff, none of that. Also there is no torque converter. No friction means no particles shed and suspended in the oil. Far less heat is generated by pumping action. There is some heat from the motor-generators and this will cause the ATF to darken over time, but you'll never feel any of it from the driver's seat.

The upshot from all of that is that a Prius is far more gentle to its ATF than just about anything else on the road. Change the fluid if you feel like it- the car won't mind. But don't feel like you need to- this isn't a Subaru/Nissan/Honda CVT.

 

Yep, should be fine. I took a risk and did one on my daughter's used 2012 Sienna and, after a year, haven't had any issues. (A very neglected van...I've changed out all the fluid and suspect they were all originals except engine oil...yikes.)

Make sure you only refill with Toyota World Standard tranny oil and have a breaker bar...those drain/fill bolts won't give up easy!!

 

I changed one Prius at 60k miles and another Prius at 100k miles. No difference in cars' performance.

However, I changed my Camry's ATF at 210k miles. The difference was obvious.

 

Looks very good for being years old and having 159,000 miles.