[acpantera]

Takes a long time. One would think since it doesn't suck water, it could occupy a closed system forever. If you've ever owned a really old motorcycle since it was practically new, you find out what lasts a long time and what goes to hell from disuse.

I think you're confusing DOT5 with DOT5.1, for some reason the numbers are similar in category but completely different in usage and composition. DOT5.1 is compatible with DOT3 and DOT4, it just has a higher boiling point. DOT5 is a silicone based fluid and is NOT compatible with DOT3, DOT4, or DOT5.1 . KTM says to use DOT4 or DOT5.1 and warns about DOT5......stupid nonsensical labeling.

 

[acpantera]

It's not all on you, the classifications aren't as clear as they should be, and probably won't be fixed till people start loosing their brakes and people are hurt or killed because someone mistakenly puts the wrong fluid in their brake master cyl.

 

[acpantera]

5.1 is not silicone .
Totally agree that using factory specs the smart and safe way to go. In our case, factory recommends DOT4 OR DOT 5.1, if I was really pushing the bike to IT'S limits I would renew the brake fluid every year with 5.1, seeing that I'm just a mere mortal that never track rides, 4 is all the I will ever need. DOT4 used in all my motorcycles, cars, trucks and snowmobiles. Never experienced brake fade in any of them.

 

[acpantera]

I guess my only reason for using DOT4 is just habit, I go through a lot of brake fluid and 4 is acceptable for most everything I work on and own. The boiling temps aren't that different from 4 to 5.1 and I know none of my vehicles will get pushed to the limits, and the fluid is seldom older than a year in my bikes or sleds. So again it's just cost effective and convenient to keep one type in stock.