And there's no actual evidence that any of this is needed. Really, where is the evidence of damage if you don't change the oil, as some of these headlines claim? It's all conjecture, based on what people think they know transferred from other technologies.

So what data do we have? Since our HS is still pretty new (and not even in Consumer Reports), let's take a look at the Prius, which has had a sealed tranny since it's introduction in 2001. Go to Consumer Reports, and you'll see that the reliability is well above average (their best score) for both major and minor transmission areas. Every year back to 2001. Based on unbiased reports from tens of thousands of Prius owners, not a few cases on some forum or some guy claiming he sees this all the time in his shop. Same with the Camry Hybrid back to when it was introduced in 07, and even the Highlander hybrid back to 06 (not sure how similar it is, but it was right there so I included it). Pristine reliability records, with almost no one ever changing the tranny fluid. For 14 years now.

How can that be? First, the CVT is nothing like a conventional auto tranny, and I'm not speaking about the motors or electronics. There's no friction belts adding particles (and heat) to the fluid. And unlike with a torque converter, the fluid does no work, so no heat creation there either. It's really more like a differential or manual gearbox, in that the fluid only lubricates the bearings and gears, and does nothing else. Sure many of those have oil that can be changed, but it's much less necessary than an auto tranny.

So if you feel compelled to replace the tranny fluid just to be safe, there seems to be no reason to do it more often than you would on a differential or manual tranny, maybe every 100,000 miles. But there's certainly no evidence that your HS is in grave danger if you don't immediately change your tranny fluid

 

It's called friction.
Yes and you change the fluid on these units.