Sorry, using memory as my only reference meant I got it arse about.
As far as I am aware, the following info is correct.:
Dot 4 has a higher boiling point than 3.
Dot 4 has more favourable hygroscopic properties than 3
But, Dot 4 can cause problems with some rubber components, and has been reported by Toyota (and Honda too, from memory) due to it missing a specific polymer or lubricant additive.
Therefore I used dot 3 when I fitted my brakes to the F15.
Dot 5 is synthetic silicone based and is OK for new/overhauled brake systems that do not have any trace of 3 or 4 remaining in the system.
Oh, yeah, there's a problem with dot5 in ABS systems from memory, just in case you were going to trick up the Blitz brakes!
