I would argue the 4th year is the important one. I'm a believer in fresh brake fluid to remove moisture and contaminants
I just had 4 year service 2 days ago. Here's a copy of my post from the tesla.com forum. Note that they didn't change brake fluid. They inspected it and moved on:
Just completed my 4 year service. Went in expecting it to be ~$700 and they do what they do. However...
As of Monday 3/18, they have a new policy. Instead of just doing stuff, now they show you a list of recommended stuff, ask you what you want done, and you pay a la carte. It was somewhat confusing, not only for me, but for the service advisers, too, as it was new to them.
I was expecting the battery coolant (or is it the brake fluid?) to be flushed and replaced. Wasn't done because they changed it to 10 years. The web site still shows 4 years for originals and 8 years for refresh, but they assured me they are correct and the web site has yet to be updated.
Bottom line, I told them to do all the recommend stuff on the list. It cost $561, which included $12 in parts and the rest labor.
The bigger items:
Alignment ($150)
AC desiccant bag replacement ($1.35 in parts and $100 labor, lol)
Air suspension torque check and adjustment ($287.50)
Wipers, fob batteries, other various diagnostics N/C
They did 2 recall fixes - steering bolts and airbag.
Also a Liftgate drain plug retrofit at N/C.
I asked for them to roll the software back to V8. They said they still get lots of complaints about V9, but cannot roll back.