Anything below 0.3V.
It's supposed to collect moisture at 1% a year, and 3% is when you're supposed to change it.
No idea how much it affects clutch feel in these cars though, if at all, even though it acts as the clutch fluid as well. Old brake fluid is just supposed to have a raised boiling point, which you'd only ever really have problems with on a track day. The road is full of cars with ancient brake fluid.
It's supposed to collect moisture at 1% a year, and 3% is when you're supposed to change it.
No idea how much it affects clutch feel in these cars though, if at all, even though it acts as the clutch fluid as well. Old brake fluid is just supposed to have a raised boiling point, which you'd only ever really have problems with on a track day. The road is full of cars with ancient brake fluid.