Brake fluid

g40steve · Jul 9, 2007

Cars having a service on Sat morning.

Is it worth putting different brake fluid in??

As mechanic will either replace original or upgrade if i supply.

What you guys got, any difference?

Cue · Jul 9, 2007

i'd put 5.1 dot in it. you may not feel the difference at everyday driving levels but if the brakes come under prolonged use you certainly be pleased with the switch - high boiling point.

160dmb · Jul 9, 2007

Seconded, I run 5.1 the Trophy, and also in my race car.

In the racecar I never ever have hydraulic probs, but some people I race with seem to.

Don't know if it makes that much difference in the Trophy in normal use, but the added safety margin is worth it.

If you are that far into it, might be a good time to go for braided hoses too......

OliS · Jul 9, 2007

I think I have boiled my fluid at previous trackdays, so I am going to get my fluid changed come service time. Was going to go for some high boiling point DOT 4 fluid though rather than DOT 5.1, Motul RBF 600 seems to be one of the best fluids with a high boiling point (312 degrees) but does not cost the earth like the Castrol SRF...

Cool Hand Luke · Jul 9, 2007

What would the advantages/disadvantages be of using either dot 4 or 5 or 5.1 on the Trophy - assuming the car is not used on the track?

OliS · Jul 10, 2007

It's all about boiling points - From what I have worked out, DOT 3 was superseded by DOT 4 which brought with it higher boiling points, DOT 4 was then superseded by DOT 5.1 for the same reason, however DOT 5.1 will absorb water more easily than DOT 4, which is one of the reasons why high boiling point DOT 4 fluids are now readily available. This is just what I have picked up from the net and talking to people, someone please correct me if I am wrong! One thing I do know for sure is that you can't mix DOT 5 (as it is silicone based), with a system that is designed for DOT 3, 4 or 5.1.

Assuming the car is not used on track, best to stick with what Renault put in there, I doubt you will need a fluid with a higher boiling point, but then again it all depends on your driving style!

160dmb · Jul 10, 2007

Well researched Oli

Deffo don't mix Dot 5 with anything else.

Correct again on 5.1 having higher boiling point and potential for going "hydroscopic" - getting water in it!

There is one other synthetic option which resists water and boils v high, and most importantly doesn't attack paintwork.

Name escapes me, but I think it comes in a Green box.

Steve · Jul 10, 2007

This confirms what little knowledge I have on the subject, I talked at length with Donkey about this while chiefbadger propped his eyelids open with matchsticks and tried not to nod off.

Basically, nobody but the army uses DOT 5 because they don't care about brake fade in a Jeep and are more concerned with it not getting contaminated by water.

DOT 5.1 is generally the best stuff, although many top race fluids come under the DOT 4 category.

DOT 5.1 for the Trophy, doesn't really matter which, but spend loads on a brand name if it makes you feel like Lewis Hamilton.

Braided hoses - don't bother, the OE ones are internally braided and less likely to rub against something, wear through and piss brake fluid all over the road before sending you off on the world's shortest Rally into a tree.

amm · Jul 10, 2007

i would put in dot 4 with a high bolling point as you need to change dot 5.1 regularly as it is a race fluid if i remember it needs changing every six months as it lets moisture build up in it this is the best option for some one that likes to do track days http://cliotrophy.co.uk/forum/garage.ph ... 11&MID=464

hoolio · Jul 10, 2007

So what is the fluid that it comes with? or is it actually french wee.

g40steve · Jul 10, 2007

Cheers, i will get them to refil with renault fluid & bleed system then.

amm · Jul 10, 2007

for track day use go for castrol dot 4 http://cliotrophy.co.uk/forum/garage.ph ... 11&MID=464 and braded hoses i run performace friction 97 brake pads and i have never had any problems with the castol dot 4 race fluid its cheep with a boiling point almost as good as some of the dot 5.1 range and is a beter than some of the cheaper dot 5.1 fluids .

amm · Jul 10, 2007

hoolio said:
So what is the fluid that it comes with? or is it actually french wee.

all new cars come with a cheep dot 4 brake fluid in the braking systems at the end of the day you get what you pay for

amm · Jul 10, 2007

g40steve said:
Cheers, i will get them to refil with renault fluid & bleed system then.

steve how old is your car ?

g40steve · Jul 10, 2007

2 years old Aug.

amm · Jul 10, 2007

g40steve said:
2 years old Aug.

it would be worth getting your fluid changed then m8

BenR · Jul 10, 2007

Castrol SSuper DOT 4, nothing more is needed for a road car.....synthetic, fit and forget, performs great and is cheap.

On a road car you'll not run into boiling fluid issues, even on track the pads will go first.