For all you who have searched for fluid capacity for the R3 forks and found nothing. Here it is 19 to 20 oz.
I just changed fork seals and oil from the bottom by removing the dampner rod bolt, lowering the leg, replacing seals and refill from top. Use an impact so the rod doesn't move during bolt removal.
Went for a ride today in the mountains (where I live) lots of corners the bike handles like new and no leaking seals! Easy job. Easier than seal job on up right forks!