DOT4 or DOT 5.1?

[BigJC]

Evening all,

Tomorrow is new brakes day, can anyone give a definative answer on whether to use DOT4 or DOT5.1?

Cheers!

[swordy21]

I would use DOT 5.1. Halfrauds list this as the recommended one as well.

Cheers

Jon

[Redbrick]

I use 5.1 with my AP kit.

I went from old dot 4 to new (obviously) 5.1 and the difference was noticeable.

Don't know whether that was due to it being new fluid or not!

If your changing the fluid you might as well put 5.1 in, no harm can be done.

Andy

[BigJC]

Thanks for the advice. The hunt for 5.1 in Warrington starts tomorrow morning!!

Cheers.
Jon.

[Engineer]

Don't forget to change it more regular than 3 or 4 as the higher the dot of normal brake fluid the more hydroscopic it is (the more water it absorbs the lower the boiling point becomes). You don't get something for nothing. You could check out dot 5 if you want to investigate further, but this can't be mixed with normal fluid.

[gazjacko]

It's a funny system with these fluids.
My understanding is yes 5 is better than 4 but 5 (silicone) is not compatable with 4 so you have to flush the whole lot at the very least before using it. 5.1 IS compatable with 4 and is better but is more hydroscopic, so should be changed more regularly (but we're not talking more than annual at most ) and the benefits of lack of fade in repeated braking has to count for something.
I speak as I find and before I did my brakes I found myself parked halfway across a T-Junction before the old ones would stop me after some 'spirited' driving

[chriskay]

That's funny; I thought silicone (5.1) was not hygroscopic. Also, seem to remember it not being compatible with certain seals.
Cheers, Chris.

[fireclown]

That's funny; I thought silicone (5.1) was not hygroscopic. Also, seem to remember it not being compatible with certain seals.
Cheers, Chris.
same hear m8.

[BlackBeast]

If you can find it use some ATE Super Blue, has a dry boiling point of 536 F and a wet of 392 F.

[gazjacko]

OK, spoke to a man in the pub tonight who reckons he knows (it was still early!).
You can get synthetic brake fluid in 4 & 5 DOT rating the higher the number the better it is (boiling point etc)
However you can't mix this with Glycol based fluids as it messes up the rubber in the seals. halfords (and others) sell a fluid that is 5.1 rating AND compatable with other Glycol based fluids so it's a straight replacement. This 5.1 stuff is , however , more hydroscopic than DOT 3 or 4 so needs replacing sooner.
All i can say is that I used 5.1 stuff and 'touch wood' it's been OK so far

[mraldonnelly]

4 or 5.1 will both be fine.

5.1 obviously better but as others have said it's more hydrowotsit.

The main benefit of 5.1 is the higher boiling point so brake fade is less likely.

DOT 5 silicone - I didn't realise this was OK to use prooviding the full system is flushed. Personally I'd steer clear and stick with 4 or 5.1.

See you later

Andy