Is 5.1 synthetic or not??

[Martiny]

Ok, I'm confused now!

After going to 4 spares shops I couldnt find DOT5.1 anywhere, and some of them didnt know what it was! - so I ordered some from Rotechniks.

It arrived yesterday, and it says SYNTHETIC in large bold lettering on the front.


Now, I thought DOT 5 was synthetic and not compatable with Dot 3, and 4. I thought DOT 5.1 was non-synthetic and compatable.

Now, on the back of the bottle in tiny print it says "non-silicone". It also says " mixes with DOt 3,4, and 5.1"

So, is it silicone that makes DOT 5 not compatable with DOT 4?

Please help, I am about to flush the system on the RX-2, and then the 7.

[Fish]

Martin, are per the label it will mix with most other version of the DOT range. The only one that doesnt mix and should not be use is DOT 5, this stuff eats the O rings and seals.

Dan

[Martiny]

Thanks Dan
So, is it the Silicone thats the problem, then?

[Fish]

Dont think its the sillycon! ;) Just there is something in DOT 5 that the seals dont like on a longer term basis.

Dan

[clive]

You may find this more suitable



R600+. The R600+ is as you know an excellent product, which today is used by leading teams in the British F3/GT Championship, BTCC, F3000, SEAT etc (all leading respective championship). The R600+ is compatible with AP600, Brembo, Motul 600, Silkolene 2000 and most other synthetic brake fluids.



However, if Castrol SRF has been used I would advice to change the seals. Normally it is not a problem if you are not changing the seals but it has proven that some seal materials are affected by SRF in such way that when R600+ is introduced seal swelling occurs which results in binding brakes.



The R600+ has only minimal seal swelling (see spec sheet) and does not cause any problem with seals if the seals has not already been affected by other fluids



Furthermore, if someone has been stupid enough to use silicone brake fluids in a high performance/racing car – change all the seals!



The R600+ can also be used in clutch systems and it is worth mentioning that the R600+ is DOT 4 meaning that it is fully legal to use on the road – i.e. usage in track day cars.



The reason that the R600+ is not a DOT 5.1 is that it is thicker at – 40ºC than required by the DOT 5.1 standard which is designed for high performance cars with ABS brakes used in artic climate. The R600+ exceeds both the dry and wet minimum boiling points of DOT 5.1 so performance wise it is much better than any DOT 5.1 spec brake fluid. It is worth mention that nobody has today managed to make a DOT 5.1 brake fluid with 600ºC + dry boiling point (being a thinner oil it will just vaporise above approximately 280ºC).



I hope that this helped.

Clive