Brake Fluid Change

[Richbot]

Is it possible that because of the regen braking that the hydraulic system isnt heat cycling like an ICE vehicle and the fluid isn’t developing condensation?

I think this makes sense. there is no such thing as a perfect seal, seals become less perfect as they heat cycle, so it follows most of the water entrainment comes from dissimilar material expansion/contraction and the pressure-equalization letting air in/out at the reservoir. If it's only rarely getting above ambient, it follows you'd need to change it rarely, or never for the life of the vehicle.

For a track car I'd change it like any other track car.

 

[SteelClouds]

I read through this with some interest. But I think there are some misconceptions. One is the amount of trust people put in the brake fluid testing strips. All those do is show moisture. They do not show degrading from excessive heat ( think track day)or someone who has the car in easy regen and just got off a road trip in the mountains and so on. This is even more a consideration in a used Tesla ( or any used car) where you have no idea as to the real history of the car or how it was used or abused. I just changed the fluid in my 2019 M3 bought used and I know it was a local car and I know it was not abused in the classic sense of the word. I know it was not driven very much at all since I bought it in 2021 with 11K miles. However, the fluid came out looking like hazy yellow pee. Ugly.. I put in Bosh brake fluid. I followed the specs of pressure bleeding at 5psi. No mess.. no fuss. and now the pedal is significantly firmer. I did all this because A: it was long over due apparently and B: I wanted a known baseline before i swap in the red performance brake system. Every time the brake fluid reservoir is opened to check allows moisture in. You may may have a bad seal thats lets in air. You may have had contaminated fluid from the factory. Who knows.. and the fluid is cheap.. even the "good" stuff like the Bosh I used is 15 per quart so 30 bucks in fluid or 15 per year. Small price to pay to keep the system in top shape and peace of mind I did spend 65 on a pressure bleeder but I have 5 cars to take care of . so I get my money's worth from most of my tools.

 

[Richbot]

Those test strips are for preventing line corrosion more than anything related to fade. Just bleeding enough to clear the old fluid out of the caliper every so often is going to be enough to keep things happy

But without a lot of heat at the caliper, the fluid will not degrade much in the absence of a seal failure or something. Cloudy yellow is still pretty good. Brown or even black is pretty common for the stuff that gets boiled or sees repeated high heat