My man, change your drivetrain oil. Call me old fashioned but vehicles should last longer than 8 years. This "lifetime transmission" stuff is hogwash. I have a 5 year old ICE car that I plan on changing it's transmission oil and filter...in about 3 years.
Your drivetrain is made out of actual materials. Not some marvel movie space metal. It will shed some metal into the oil when it moves. You don't want to drive around with grit soap for lube.
Dude, this is utterly ridiculous nonsense and no one should be having their Tesla motor drive units cracked open to change lubricants. Not only does it void the 120k mile warranty, but it proves you have no experience with them.
You may as well be telling me to have my rear diff rebuilt on an MX-5 after 10,000 miles.
No, I don't have experience working on Teslas, you didn't address my concerns though. My concern is with ANY moving part. I don't need to be an Tesla certified engineer to tell you fluids that keeps things moving, cool, clean need to be changed at some point in time.
If that amount is what's normal for them than then that's fine, that's why I said to check your owners manual.
If the mileage is that low for your mx-5 then that's probably warranty if your rear diff does need rebuilt. So that is good news.
Look, even if the fluid change interval is longer than 120k miles and would coincide with a rebuild, it's still an interval, not "lifetime." I mean, you wouldn't rebuild the part and put back the old fluid, would you?
My oil is hard and strong. Like all the hardened steel inside the fluid. We've built up years of trust and bonds. You don't think the gear oil would do me like that. It's like marriage, for life right?
It isn't an interval, though, it is lifetime. I'm apparently continually failing to make that point.
120k is only the warranty period on the drivetrain/battery, and I'm using it as an example, for parts that have zero maintenance, and are guaranteed for an amount of miles most people never even put on an ICE vehicle that otherwise requires oil changes every 3k-5k miles.
put back the old fluid
Irrelevant. Even being in the position of having a drive unit serviced at all is outside the norm or intent for lifetime of the vehicle.
an amount of miles most people never even put on an ICE vehicle
Maybe most first owners never put that many miles on their vehicle, but lots of vehicles do, in fact, get that many miles on them eventually. Those subsequent owners need to understand that "lifetime" isn't really "lifetime" and that those fluids actually do need to be changed at some point!
At a point where a drive unit has to be rebuilt, it's going to be hundreds of thousands more miles than an ICE would have on it when it requires a rebuild, and engine rebuild means "lifetime" is over. It's effectively a new engine after that.