DOT5 is Silicon based, which is MORE compressible than Polyglycol fluid. Your brakes will feel worse.

It does NOT absorb water, so the boiling point will remain pretty constant after several years. But if additional water is introducted then that will boil at 100°C, giving you no brakes anyway.

Some seals can be damaged I think, but the main problem is that it's less lubricating, so the seals wear more, and the fluid is more prone to airation, so it's REALLY hard to bleed.

DOT5 tends to not eat paintwork, but you have to be a bit stupid to spill it on your car anyway.

Only a complete muppet uses DOT5 fluid, because it's rubbish.

Quote from tristancliffe :

DOT5 is Silicon based, which is MORE compressible than Polyglycol fluid. Your brakes will feel worse.

It does NOT absorb water, so the boiling point will remain pretty constant after several years. But if additional water is introducted then that will boil at 100°C, giving you no brakes anyway.

Some seals can be damaged I think, but the main problem is that it's less lubricating, so the seals wear more, and the fluid is more prone to airation, so it's REALLY hard to bleed.

DOT5 tends to not eat paintwork, but you have to be a bit stupid to spill it on your car anyway.

Only a complete muppet uses DOT5 fluid, because it's rubbish.

Cheers for the clearup, all I heard was rumors. Your statements tend to revolve around facts so

Racing Dot3 for me here, Wilwood 570 Dot3. Which reminds me... I could another change out again.

I dont know why srf says its dot4 but they say the same thing about the motul rbf600 and that is rated far above dot 5,

This site has a good chart at the bottom for comparing fluids

http://www.volvoclub.org.uk/faq/BrakeFluidComparison.html

The ate super blue fluid (which is dot4) on that list shows fluid temps far above the spec of dot5 so does that mean ate have got it wrong?

And i think the main problem with seal damage is when you mix dot 5 with 5.1 (but im not certain) you have to make sure if you change fluids you remove all the dot5 first.

Silcon does absorb water, infact it absorbs water hugely. Sorry I don't know anything about break systems but from my knowledge of fluid dynamics I would think that less fluid compressability and the fluids ability to reamain cool would be major factors in a breakin system effectiveness. Also where is the moisture being absorbed from in a close loop system?

Fluid compressability for most of the calcs I do is assumed negligeable, the expansion in the system is more affected by the tubing or god forbit thermoplastic hosing.

In 50km long hydraulic pipework fluid compressabiltyit does have a major effect. (Remote subsea hydraulic control systems).

Also from my experience synthetic oils are way more hyGroscopic than mineral based oils. Ensuring that the brakes a bled properly and completely I would imagine is very important as air as we know is most compressable.

Soory for the ranting nonsense I've had the day of work and been in the pub

I was under the impression (which is confirmed by half a dozen websites I just Googled to check) that Silicone brake fluid is not hygroscopic.
More compressibility is a huge factor, and is why DOT5 brakes feel horrid. Try it and feel for yourself - it's marked.
A brake system isn't a sealed system - there is still a vent to atmosphere, and the water comes from that.

Fluid compressibility is a major factor in braking systems where 100bar is not uncommon. but yes, hoses expansion is another factor.

Synthetic oils may well be more hygroscopic than mineral based, but that's another topic altogether.

The trouble is that watery brake fluid boils, and produces compressible gas. This is why using racing brake fluid, which is a LOT more hygroscopic [and expensive] is a stupid thing to do. It's also why race cars using fluid with a higher boiling point. But I'm sure you knew all that.

The disc brakes on my Mountain bike use DOT 5.1 oil

Sometime when you buy certain item like bags, laptop cases for example (I don't make a habit of buying handbags...honest!) there is sometimes a little bag filled with small silicon balls it is there to absorb any moisture present in the air...try putting them in your mouth and see if they absorb moisture or not

Oh dear this thread has gone way of topic

Quote from RocksGt :

By the way... a few weeks ago I've test driven a new MX-5 (2.0 160 bhp)

A MX-5 is a cliturus car because every C**ts got one. Just added that said that to a few men who have had one, said it to someone when I was in hospital who had one, he didn't know where to look and his mates just laughed at him.

MX5 model from 1980 is pure awesome (besides that, its cheap) but the new MX5 aint that pretty :-/

Quote from sam93 :

A MX-5 is a cliturus car because every C**ts got one. Just added that said that to a few men who have had one, said it to someone when I was in hospital who had one, he didn't know where to look and his mates just laughed at him.

Is your avatar an accurate representation of you?

Quote from ajp71 :

Is your avatar an accurate representation of you?

No

Quote from AlienT. :

there is sometimes a little bag filled with small silicon balls it is there to absorb any moisture present in the air...try putting them in your mouth and see if they absorb moisture or not

No, that ISN'T silicon, it's sodium silicate (silica). And it sometimes contains toxins. That's why the bag says "DO NOT EAT"!

Quote from Math1js :

MX5 model from 1980 is pure awesome (besides that, its cheap) but the new MX5 aint that pretty :-/

damn I need to get a 1980 MX-5. Is it like a pre-prototype edition?

All we have in the states is the 1990 model (released in 89), which for the most part went relatively unchanged mechanically through 2005, and the new chubby redesign released as an 06 model.

Quote from sam93 :

A MX-5 is a cliturus car because every C**ts got one. Just added that said that to a few men who have had one, said it to someone when I was in hospital who had one, he didn't know where to look and his mates just laughed at him.

Do you mean I would turn in a complete **** being ashamed of my penis and worried about my mates' words if I own a MX-5?

Don't get the point of the hairdresser's car stuff... I think... maybe for being a spanish "macho" I'm not measuring my penis with my car

Quote from RocksGt :

Do you mean I would turn in a complete **** being ashamed of my penis and worried about my mates' words if I own a MX-5?

Don't get the point of the hairdresser's car stuff... I think... maybe for being a spanish "macho" I'm not measuring my penis with my car

No, it's just a little joke, because it is mainly classes as a womans car and when you see I see a man drive on I say that, because it is normally a girls car. Why be ashamed to drive it, if you like the car you can drive it.

Quote from sam93 :

No, it's just a little joke, because it is mainly classes as a womans car and when you see I see a man drive on I say that, because it is normally a girls car. Why be ashamed to drive it, if you like the car you can drive it.

This is what I call a girls car

Quote from sam93 :

No, it's just a little joke, because it is mainly classes as a womans car and when you see I see a man drive on I say that, because it is normally a girls car. Why be ashamed to drive it, if you like the car you can drive it.

I believe studies over here show more women drive V6 mustangs than miatas, not only in sheer numbers, but percentage of male vs female buyers as well. The same people who class it as a "women's car" are the same people driving real women's cars....

Quote from Technique :

damn I need to get a 1980 MX-5. Is it like a pre-prototype edition?

All we have in the states is the 1990 model (released in 89), which for the most part went relatively unchanged mechanically through 2005, and the new chubby redesign released as an 06 model.

wups, mistyped

If one likes how car drives and such, he buys he, let it be even Britney type of car, who cares? Car is for one that buys it, right? Surely everyone has enough self confidence to get car he likes without thinking such things

Be careful when looking for an MR-S. Much engine problems because of pre-cat failure , excessive oil usage can be a result of little cat particles sucked back into the engine. Be wise and look out for one that had the engine replaced not too long ago and/or one which had the pre-cats removed (you can fit an aftermarket header which solves the problem). Other then that, terrific car but bit underpowered.