Brake Fluid

[shemat]

I'm thinking of changing my brake fluid from DOT to the silicon stuff. I'm hoping that as this won't obsorb water I'll have less trouble with cylinders seizing. Do I need to change any components and how should I flush the system through? Is it a worthwhile plan?

Thanks

Matthew

[taupe]

If your going to use silicone you should really change all the brake lines cylinders and seals.

I think that the silicone can stand a small quantity of conventional brake fluid but its not worth the risk.

[bmcecosse]

DON'T DO IT ! It's really really not worth the hassles - no modern car uses it. It's a MUCH over rated product.

[Stig]

I've had no problems with it, except the cost - it's seriously expensive these days!

[rayofleamington]

If you prefer taking your advice from people who've done it and not the scaremongers, I've also used silicon and had no problems whatsoever.

There are documented cases of the fluid change causing old seals to swell and fail - fluid seals are not 'inert ' and the material changes depending on the fluid it contacts with. Old seals are a bad idea anyway so one that has had an un-known life with another fluid shouldn't be re-used with a totally different fluid.
However if the cylinders are all fairly new, and you've not had overheated brakes, then the probability of getting a seal problem is very low. When I did mine I replaced all the cylinders anyway.

[Alec]

Hello Mathew,

I'm with Ray and about 25 years of using Silicone fluid and I would use nothing else.
Modern car manufacturers don't use it because it's more expensive and cost is everything when building cars, although, apparently, Harley Davidson motor cycles are factory filled with silicone.

Alec

[simmitc]

And another vote for silicone. Two travellers use it, the saloon has conventional fluid. All get similar use, but the saloon suffers more seized cylinders than the travellers. More importantly, it doesn't ruin the paintwork if you spill any!

[polo2k]

It does sound like its good stuff but i never have any problems. I used to use Dot 5.1 for a bit more boil resistance in an previous car but now I use standard Dot 4/5 and have no problems.

If someone made an oil that you never had to change and that didnt oxidise, I wouldnt leave it in an engine for ever. I would still change it as normal.
I see brake fluid as a consumable and dont mind changing it every so often. Cost isnt as issue really (its only a few quid) and it doesnt take long once you have gerry rigged a pressure bleed. You can do it while greasing.

Besides, if there is any muck in the system (grit or swarf) I would rather flush it out. On the same note, if there is a bit of water in the system I would rather it got dispersed through the fluid rather than sit as a bead against the inside of the brake line, I could imagine that being a terrifying failure (in a worst case scenario).


While on the subject of brake bleeding, http://cgi.ebay.co.uk/Speed-Bleed-Nippl ... 5d24d351db
you would need the right thread obviously.

They make things so easy, on the bike you just open one, pump a few times then lock it off. Instant bleed with no leaks.

[Neil MG]

23 years using silicon and I can also highly recommend. The big plus is not having to change every two years and not having to worry about spills when you bleed the brakes! I have heard many people complain that they have had problem with seals etc. using silicon fluid and it is of course perfectly fine to use DOT 4 too. Each to their own as there will never be total agreement!

One thing to note though, silicon fluid is NOT compatible with other brake fluids and they should not be mixed!

[bmcecosse]

Normal fluid is fine in my car with it's superior Wolseley brakes - and I certainly don't change it every 2 years. I do usually bleed a little through each nipple before the annual MOT, mainly to make sure the bleed nipples don't seize up - that's all!
I like to keep my Minor motoring nice and simple - good luck changing all the seals - especially the master cylinder......