The top lid on my handlebar reservoir, '02 640a, says "Use Dot 4 Only".
I used some Dot 3 cause I was leaving for Central America and was in a rush. I lost the rear brake completely coming down a volcano to Lago Atitlan in Guate.
Problem cured with Dot 4.
Speciality item in Guatemala small towns.
Scares me to see blown out USA school buses coming down the mountains with Dot 3 in the system, teen age drivers shifting gears like crazy.