Topping Up Break Fluid Dot 4 Or 5 ?

[Longz]

Hi All ,

Noticed today that my break fluid levels are running low , i guess its fairly easy to top up

was thinking of getting motul however there's a DOT 4 and DOT 5

Which one is better ?

Also i currently do not know what brake fluid is currently in the car do i need to flush it to be safe or just top up ?

Car is GTR34 .. Thanks.

[jrm]

You should, ideally, use whatever the car is running now. If you don't know what's in there now, I'd probably suggest DOT4 (though I seem to recall it may say 'DOT3' on the lid). That said, if you don't know what's in there, it could be a good opportunity to flush the entire system and replace it with fresh fluid.

Anyways - DOT5 is silicon-based not glycol-based and isn't typically used in road cars. It also isn't "compatible" with other brake fluids (DOT3/4). That said, you may be confusing it with DOT5.1 (sorta like a 'better' DOT4).

See:

http://en.wikipedia.org/wiki/DOT_4

http://www.motorcycleproject.com/motorcycl...brakefluid.html

for details on the differences.

[Birds]

Straight forward DOT 4 unless you do a bit of track work in which case you can try for something of higher temp. But if using a different DOT to what you're currently running, make sure you flush the entire system thoroughly - using the new fluid. May need a couple of bottles to do it.

[Longz]

just had a look at the lid it says use DOT 3

My mechanic told me to go with Motul Dot 4 ( CRD )

any ideas ?

[djr81]

just had a look at the lid it says use DOT 3

My mechanic told me to go with Motul Dot 4 ( CRD )

any ideas ?

Believe your mechanic.

You won't find Dot 3 fluid anywhere. Dot 4 is the replacement so use that.

Dot 5 is a mutant offspring and should not be used.

If you want track biased fluid get dot 4-600 which is a high temp dot 4 fluid.

[Birds]

You can find DOT 3, but there's no point to using it. DOT 4 will cover and work in all DOT 2, DOT 3 and DOT 4 systems

[Longz]

ok guess ill go with motul dot 4 , as i dont know whats previously be put in should i flush it out or should i be alrite just putting 4 in ?

[Moodles2]

DOT3 and DOT4 are supposed to be chemically compatible so you can mix, but over time the boiling point of brake fluid gets lower and lower as the fluid takes on water from the atmosphere. If the current fluid is black it would be worth getting it bled out and new fluid put in.

[TurboDoseBro]

So that means we can just ignore what the lid says (use only DOT 3 brake fluid)? I have read the link.

DOT 5 is silicone and DOT 5.1 is glycol.

How frequent would one have to change DOT 5 (silicone) brake fluid compared to normal 5.1? Is it worth it?

Currently have stock GTS-T brakes and will be getting Bendix Ultimates to accompany the new fluid. Will start doing a bit of track work soon too.

Thanks.

[hmd993]

how do you flush the brake system of fluid?? and how many liters will it require to fill it again with new fluid?

[08yannch]

how do you flush the brake system of fluid?? and how many liters will it require to fill it again with new fluid?

well i did mine my by following the bleeding procedure but i bled each caliper until the new brake fluid came through.

thinks to do

-keep the brake fluid above the min mark on the brake u must do all u can to keep air from getting in the system

-try to keep the caps on all the brake fluid to minimize water absorption from the air

-i think i got by with one bottle of brake fluid (no idea in ml there all pretty similar though) but 2 is ideal. just so u have some on hand just incase

any 1 want to add to this go for it

[08yannch]

So that means we can just ignore what the lid says (use only DOT 3 brake fluid)? I have read the link.

DOT 5 is silicone and DOT 5.1 is glycol.

How frequent would one have to change DOT 5 (silicone) brake fluid compared to normal 5.1? Is it worth it?

Currently have stock GTS-T brakes and will be getting Bendix Ultimates to accompany the new fluid. Will start doing a bit of track work soon too.

Thanks.

DOT 5 is really not for u hear is why.

ur brake system has a glycol based brake fluid in it now and glycol brake fluid absorbs water. when u bleed the system for dot 5 u will not get all the glycol brake fluid out and when the brake fluid gets hot u will have steam in ur brake lines this is bad.

dot 5 needs to be bleed a lot more then glycol brake fluid because if any water gets in u will get corrosion because the dot 5 will not absorb water, this is why the u get steam in the above section.

most ppl will use dot 4 and nobody has problems with it. i dont know about dot 5.1 but i have heard it will make ur ABS angry.

[Longz]

DOT 4 Completed.

Got a mechanic to suck out the liquid using a machien gun thingo from the brembo calipers and top up..

[Moodles2]

Lucky you didn't take the advice here and put DOT 5 (Silicon), as silicon will eat away at your rubber brake hoses and rubber seals.

[hmd993]

well i did mine my by following the bleeding procedure but i bled each caliper until the new brake fluid came through.

thinks to do

-keep the brake fluid above the min mark on the brake u must do all u can to keep air from getting in the system

-try to keep the caps on all the brake fluid to minimize water absorption from the air

-i think i got by with one bottle of brake fluid (no idea in ml there all pretty similar though) but 2 is ideal. just so u have some on hand just incase

any 1 want to add to this go for it

wouldn't that method get the old and new fluids mixed?? i read somewhere that you shouldn't get them mixed because it is bad,, btw i am going to use dot 5.1 for the new fluid and that is why i dont want them to be mix,, thanks for your reply

[08yannch]

Lucky you didn't take the advice here and put DOT 5 (Silicon), as silicon will eat away at your rubber brake hoses and rubber seals.

oops forgot about that.

another good reason to not use dot 5