Dot 5 silicon brake fluid Question

[Jerrytom161]

When i restored my standard road going Mk1 Mex it was recommended to me to put Dot 5 Automec silicon brake/clutch fluid in the systems as it has the advantages of :-

1:- never having to be changed as it doesnt absorb moisture 

2:- wont damage the paintwork if it ever leaks . 

It has been in the car a year now and i have had no problems at all . But i have heard that this is not road legal in a road going car and an Mot failure . It passed the Mot last year but i am not sure if the tester was aware of this or turned a blind eye so to speak . He never commented to me about it  , apparently  it is down to the colour of the fluid to recognise the Dot of the fluid . I was quite surprised to find this out as a lot of classic car  companies  promote Automec and products alike to be fitted into their road going cars . The systems on the Mex were all brand new eg, seals etc , i have read that the fluid can affect  some rubber parts depending on the compound used causing them to swell and become ineffective and cause failure , Has any OSF members heard of or had any experience of this issue ?  I have an Mot booked this morning and fingers crossed it will pass !!. And the issue wont arise . 

[RWL81P]

harley davidsons all use dot5 from the factory. i use it in mine and never had any problems and yeah it dosent damage paint. but as i said harleys are made to use it so no problems with rubber swelling.

[steved35]

I think old jags had it in them , I've always used it never failed mot 

[colr6]

Have these brake fluids really improved?? Back in my day fluid was never changed, yes I know we have higher brake temps now so making the fluid more suseptable to boiling and so on. You go in any motor factors and see the amount of calipers they keep on the shelf !! So has the fluid improved ....don't think so. Take a car in for service 18months old....sir your brake fluid needs changing excess moisture in it.....WHAT !.....by the way that's £85 plus vat sir. I'm still using dot 3 that's been on the shelf for ages, calipers been on for ten years still work fine. So really who's kidding who ? It's problably all the additives their putting in the fluid that's shafting all the seals up ! Stick with good old fashioned stuff everything's hunky dory.

[Rally Pack 2000]

While it doesn't absorb moisture and evenly distributes it through the fluid as lower dots do, the moisture in Dot5 pools and can corrode lines and things at those points let alone the danger of excessive heat vaporising that collected moisture in one incident. If you change it regularly though these issues wont occur but for the lazy maintenance guys that don't want to change it every year because the car has only done a few hundred miles then it can seem like having to over service. Having just repainted the inner guard because the bias valve burst, I an see the desire for a less corrosive alternative. So im still on the fence at this stage.