I need to assemble a hayes brake but I can't be arsed to buy dot 4 fluid for it so I thought I might use shimano hydraulic fluid.
Has anyone else ever done something similar this to catastrophic effect or is one hydraulic fluid pretty much like another?
Don't do it!
The other way round is worse (DOT fluid into a mineral oil brake) but it's still pretty likely that the wrong fluid will trash your seals.
don't worry about, and while you're at it don't waste the shimano fluid - use water instead
I always new dot 4 was corrosive but shimano fluid seems pretty stable so I thought it would probably work. Still I like the water idea, I think I'll go with that.
shimano is a mineral oil, DOT is a completely different make up. Seals etc... prob wont like different fluids.
Wrong fluid usually wrecks the seals, voids the warranty and requires a complete total clean and rebuild, it's not worth it!
Good troll JonR!
i remember opening up a customers hope mono mini once who brought it in complaining of it sticking badly having very recently been bled by another shop
Turns out the other nameless local shop stuck in shimano fluid - noticable as soon as it was opened.
So i wouldnt recommend it , there is a reason they reccomend a particular fluid ....
i asked this question, as mineral oil is not as corrosive to work with as dot and wanted to put it in my nines, and got some pictures posted of a test someone had done.
a few hours and the seals will be shot and ruined.
water will work fine!
just dont get the brakes over 100degrees (ie: dont brake)
i hear veg oil is ok too.....
temporarily though.
no it will be fine I run my diesle on petrol as it is cheaper.
Water wont work not viscous enough but try veg oil
DOT 4 and DOT 5 are interchangable, would try the Shimano stuff though.
Know of someone who used water as a trail-side bodge after ripping the hose off a Magura HS33, worked so well he left it like that.
Water will work, but water screws up DOT 4 and 5.1 by reducing the boiling point. You'll find it difficult to guarantee that all of it's out, so you'll have to bleed through and waste a lot of brake fluid. Why not just assemble it and bleed later? Normal car or motorbike DOT fluid is fine, and easy to get.
DOT 5 is NOT interchangeable with other DOT fluids - it's silicone based, and again, screws up seals if the system isn't designed for it. DOT 4 and 5.1 absorb water, reducing the boiling point of the fluid slightly. DOT 5 is not miscible with water, so any water in the system finds its way to the lowest point - the caliper - and boils somewhere around its normal boiling point, which isn't good.
So DOT 5 and DOT 5.1 are not the same and should not be mixed?
DOT 3, DOT 4 and DOT 5.1 are similar fluids and can safely be mixed with each other.
DOT 5 is totally different and must not be mixed with anything except more DOT 5
I bled a set of HS33's with olive oil once!!
EDIT. Meant to say 'wouldn't' above, not 'would.' Hope you have not followed my advice...
> Meant to say 'wouldn't' above, not 'would.' Hope you have not followed my advice
You also stated that DOT 4 and 5 are interchangeable, which is incorrect 
Good troll JonR!
I bled a set of HS33's with olive oil once!!
I'd heard this could be done but I thought it was an urban myth. Hope they worked okay.
Or you could just buy some dot fluid?
It was on an old trials bike of mine. We just did it for a giggle. Felt ok, not quite as responsive if anything. No idea how it will deal with heat as you dont really get much heat build up riding trials. Flushed it back through with proper fluid the next day.
Goog off here once got half way round the Gap road and had to top his brakes up with chain oil as they were pulling to the bars. I think he said it trashed his seals though. They were hopes, btw.
Noticed my front brake (Shimano) had lost fluid at went spongy the beginning of a long ride last year starting a long way from home or a bike shop (with any oil anyway) so got some sunflower oil from a local shop. topped up and bled them on the side of the trail. the remainder of the litre of oil (about 995ml 
) was dropped of in the next bin
worked perfectly 
In fact I ended up leaving it in there for about 6 months before I bothered to bleed 'em and put the proper stuff in, only did it 'cos I felt I should!
They were still working 100%
so not a myth at all
wouldn't have done it with Dot 4 brakes though
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