none of them are "compressable" - liquids after all.. BUT the differantiator between performance is their boiling temps.. boiled fluid IS compressable cos there's gas pockets created, henc elong to no brake pedal.. which is a scarey thing from personal experience. 
Yumann said:
I wouldn't know but DOT4 is glycol based and DOT5 silicone which is rarely used on road cars.
dot 5.1 is the common fluid used. Avoid silicon one like the plague.
Super Dot4 from Castrol is pretty good stuff.
How hard do you use your brakes?
What colour are your disks?
Super Dot4 from Castrol is pretty good stuff.
How hard do you use your brakes?
What colour are your disks?
I went for castrol super dot 4 as opposed to dot 5.1.
I'm not too sure on the differences but believe the super dot 4 to have a better quality and a higher boiling point than 5.1. Both are better quality than dot 4.
I was also advised to stick with a brand name such as castrol etc and not cheap crap 5.1 or super dot 4.
I'm not too sure on the differences but believe the super dot 4 to have a better quality and a higher boiling point than 5.1. Both are better quality than dot 4.
I was also advised to stick with a brand name such as castrol etc and not cheap crap 5.1 or super dot 4.
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Isn't the different between DOT 4 and DOT 5.1 that DOT 4 can absorb moisture from the atmosphere and DOT 5.1 can't which means it lasts longer?
I thought i read that somewhere on these forums once.
I thought i read that somewhere on these forums once.
none of them are "compressable" - liquids after all.. BUT the differantiator between performance is their boiling temps.. boiled fluid IS compressable cos there's gas pockets created, henc elong to no brake pedal.. which is a scarey thing from personal experience.
when i drive my car hard i have no brake pedal it goes all soft and compresses really easy its major brake fade could this be the dot4 fluid causing this .. i used to run comma dot 5.1 and seem fine
now just reading this made me think
karl whens the last time it was changed and how heavy and regularly are you going on the brakes? Fluid replacement is recommended at 2 years as it absorbs water which reduces its hydraulic properties. Fluid that is opened long before it is to be used is just as bad as it should be used immediatly, if it sits on the shelf after the foil lid is popped i wouldnt hold onto for more than a year as it will be absorbing moisture the whole time its there. Good super dot 4's can often be better than cheap 5.1's. As my LCR doesnt get hammered on the brakes regularly ive gone for the febi dot4 plus from vwspares as its £5 a litre and is rated at 260deg dry which isnt far off the castrol super dot4 at 280 deg and at that price i can afford to replace it more regularly.
i have bleed them loads and even a garage bleed them for me and still no better it happens when i sit in traffic and on off on off the pedal it goes spongey , also if i do hammer it round it compleatly gose soft
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