Brake fluid

[David Wiltshire]

My Japanese spec VX brake fluid needs topping up, I have tried to obtain DOT3 as it states on the cap but so far no luck. Having read on the cans of DOT 4.1 and 5 that it exceeds the spec of DOT3 I am a little wary as the existing DOT3 may be synthetic and the DOT 4.1 or 5 may be a different base material can anyone shed any light on this subject?

[Green Dragon]

Dot 3 &4 are Glycol based & absorb water. Dot 5 is silicone based and does not absorb water. You state that you are topping off. Do not use Dot 5 to top off brake system with Dot 3 already installed. Actually consider draining & flushing the Brake system & refill with Dot 5.
Dot 3 & 4 also have lower boiling points then Dot 5

Bob

[Dallas4u]

Would it be safe to say that Dot 5 is superior to the others?

[Green Dragon]

Originally posted by Dallas4u
Would it be safe to say that Dot 5 is superior to the others?

Since Dot 5 does not absorb water there is always a chance that if water somehow enters your brake system it will cause rust wherever it is contained.

Bob F

[David Wiltshire]

Thanks for your reply Green Dragon, as I am only topping up I will use the readily available DOT4.1