What if I switched DOT fluid for mineral oil?

  • This topic has 37 replies, 30 voices, and was last updated 2 years ago by  daern.
Viewing 38 posts - 1 through 38 (of 38 total)
  • What if I switched DOT fluid for mineral oil?
  • ferrals
    Member

    I’m looking at new bikes but a) I’m a clumsy clutz, b) I like to do my own maintenance and c) I over-think things. Therefore I’m not keen on the corrosive properties of DOT fluid. This rules out all bikes with SRAM brakes. Would it be viable to totally drain all the DOT fluid out, flush through a few times and then replace with shimano mineral oil or would the different fluid properties totally mess up braking?

    Premier Icon jimdubleyou
    Subscriber

    I have a feeling this does something like rotting the seals around the pistons, thereby rendering your brakes useless.

    That might be the other way around though…

    …not much help, sorry.

    Premier Icon dangeourbrain
    Subscriber

    As above, highly likely to leave your brakes useless as it doesn’t play nicely with the seals

    P-Jay
    Member

    As above, it’s the seals you have to worry about – Dot fluid is more corrosive than Mineral Oil, but it doesn’t make it inert. It would be a bad thing.

    The latest SRAM brakes are meant to be very good, just wear gloves and clean everything after your twice a year bleed (if that).

    Stevet1
    Member

    Just take the brakes off when you get the bike and sell them. Or if you’re buying from an LBS, try and work out a deal with them to swap the brakes?

    PJM1974
    Member

    The seals in your brakes may well rot from the inside out, making for an expensive repair job.

    If you like mineral oil, then Shimano is probably your first port of call.

    mikewsmith
    Member

    Do not swap the fluid over.
    Also don’t be scared of DOT just get a bag of rags and clean it up – just the same as mineral oil

    ferrals
    Member

    I figured that would be the case. @stevet1, cyclocross bike so integrated brakes / shifters.

    I think will stick with aiming for shimano, I also have all the bleed kit and a 2/3 full big bottle of shimano oil.

    Stevelol
    Member

    Sometimes I wonder how people get themselves dressed in the mornings.

    Just be more careful with DOT and get on with your life 😀

    Marko
    Member

    Or use Dot5 fluid. Silicone based and non corrosive:
    Brake fluid

    Controversial? Will it kill you (or more likely your brakes)?

    trail_rat
    Member

    you have looked at the msds for shimano mineral oil before thinking its any better than dot right ? might not corrode your frame but has a whole host of other issues along with the added complication of not being rendered inert by addition of water.

    anyway Mineral oil brakes use NBR seals and dot brakes use EDPM seals
    .
    contamination with wrong fluid will cause swelling of one and the other goes brittle. – either way the brakes dont really work too well 😀

    If your really clumsy and dont mind your brakes boiling you can use water in mineral systems.

    Premier Icon teethgrinder
    Subscriber

    I’m struggling to see the issues with DOT. The volumes involved are tiny and it’s a piece of piss to clean.

    Do people bleed their brakes using babies faces or something?

    milky1980
    Member

    I find DOT fluid much easier to clean off the bike than Shimano Mineral Oil!

    Premier Icon neil the wheel
    Subscriber

    ^that really. DOT is neutralised by water so keep a plant spray bottle handy and use kitchen roll to wipe up drips. Wear nitrile gloves and eye protection if you are super-anxious.
    DOT 4 and 5 are not compatible.
    DOT 4 and 5.1 are interchangeable.

    Premier Icon Yak
    Subscriber

    Occasionally I get a quiet moment and can bleed brakes tidily in peace. More often than not I am trying to get it in done in a hurry with kids mucking about and cooking tea at the same time. In this scenario I, without fail usually, somehow get mineral oil everywhere. Putting the stuff in a supersoaker and aiming upwards would probably result in less mess.

    I reckon I should switch to veg oil 🙂

    Anyway, the answer is no, don’t swap dot for mineral oil.

    Rockhopper
    Member

    How often are people fiddling with their brakes to make this an issue? I hardly ever touch mine.

    Premier Icon woodster
    Subscriber

    I find DOT fluid much easier to clean off the bike than Shimano Mineral Oil!

    True.
    I’ve done a couple of rushed car park bleeds with both and never had an issue.

    elliptic
    Member

    The thing that is annoying about DOT fluid is it absorbs moisture from the atmosphere ** so you can’t leave it in a half empty container. You end up buying it in small amounts, expensively, and having to throw away the surplus.

    Mineral oil you can buy cheaply in bulk and keep it on the shelf for ever.

    ** except DOT 5.0, which isn’t compatible with SRAM brakes anyway…

    Rockhopper
    Member

    £5.99 for half a litre of 5.1.
    DOT 4 is even cheaper, around £3.40

    stevextc
    Member

    I’m struggling to see the issues with DOT. The volumes involved are tiny and it’s a piece of piss to clean.

    Do people bleed their brakes using babies faces or something?

    My 7yr old can make a mess with a hosepipe let alone brake bleeding…. he invariably makes a mess when bleeding brakes but so long as the pads are out it can be cleaned up… I’d not trust him with DOT fluid…as half the time it ends up on him….equally how else will he learn…

    I’m usually OK except last week I was getting air out the syringe/bleed tube and a moments carelessness/stuck syringe and squirted in my eye….

    I’m rather glad it was mineral oil.

    Don’t leave it open? All i do is decant 30-40 mil into a glass beaker and then pop the bottle back on a shelf with the top done up (tightly). The volume of actual water in the air above the oil in the bottle is utterly miniscule, far too low to actually make a difference the next time you decant 30-40 mil, or the time after.

    Maybe if you bought a 5 litre bottle and kept it for 10 years opening it up 3 times a week it’d hurt, but half a litre opened once or twice a year and only opened in a nice warm dry workshop……. I’d not loose any sleep over it.

    Premier Icon Yak
    Subscriber

    How often are people fiddling with their brakes to make this an issue? I hardly ever touch mine

    Probably 1 bleed per year per bike if there is no buggering around with set-up. The thing is there is lots of buggering around, and then there’s growing kids and moving stuff between frames needing new hoses, then there’s the inevitable caliper failure at some point in the year on someone’s bike etc..

    trail_rat
    Member

    I’m rather glad it was mineral oil.

    So you have read the msds on it and are happy its on his skin. At least chemicals in dot can be made inert by a dousing with water.

    He can thank you later for all the disorders that mineral oil can be cause or be contributory to.

    Better to wear gloves and eye protection when working with either both are bad for you.

    ahwiles
    Member

    ghostlymachine – Member
    …only opened in a nice warm dry workshop…

    there’s less water in cold air, just saying…

    (only open the bottle on a cold day in january?)

    The thing that is annoying about DOT fluid is it absorbs moisture from the atmosphere ** so you can’t leave it in a half empty container.

    Yes but that also means you don’t end up with moisture lurking down at the caliper, waiting to boil when the brake gets hot, as with mineral oil systems.

    trail_rat
    Member

    in the spirit of the useless helpful comments in the touring thread of take less stuff ….

    have the regular brake boilers tried not braking as much – or at least not dragging them between points where braking is required ?

    😉

    deadkenny
    Member

    Guide brakes rarely need touching. Have shortened cables even and not needed to bleed them.

    DOT fluid is nasty if you spill it and don’t clean it up, but other than that it’s fine, and the boiling point is higher which is why it’s used. Less brake fade when the brakes get hot. But yes, keep off the brakes is also an option.

    Personally I like the modulation of Guide brakes also. Shimano is too binary for my liking.

    Stevet1
    Member

    On a related note, and I’m sure this is a common question but forgive me for asking it again, last night I made a pooter to hoover up the army of aphid farming ants scurrying around the indoor rose which has miraculously survived since valentines day. Anyhoo all perfectly normal up til now but the only tubing I could find I quickly came to realise had been used previously for bleeding my hope brakes, and after sucking up 50 ants into the schwartz oregano jar I was using as a container my mouth tasted distinctly brake fluidy. Am I likely to die from the effects?

    joefm
    Member

    Brakes are sealed and unless you have fits when changing fluid its not an issue.

    Water cleans it off anyway (DOT 4)

    Premier Icon DezB
    Subscriber

    Anyhoo all perfectly normal up til now

    Are you sure, Steve?

    Premier Icon IvanMTB
    Subscriber

    Not sure, but other way – oil into DOT 4 – in Shimano cheap brakes made no difference.

    As far as I know test lasted 6 months and still going strong.
    Dot 4 in Shimano

    Cheers!
    I.

    And Dot5.1 in shimano screws it in about 2 weeks. (not mine, a mates brakes, he wondered why the levers were sticking and the pads dragging…….

    ”ahwhiles” wrote:

    there’s less water in cold air, just saying…

    But lots in my unheated garage compared to the centrally heated and dehumidified workshop.

    How often do you bleed brakes for this to impact a purchase decision? Especially on a CX race bike- it’s not like you’re cooking them on long Alpine descents!

    Premier Icon molgrips
    Subscriber

    Why do people bleed brakes on a regular basis? They’re sealed.

    Not quite. you have shafts moving through seals, that aren’t very well protected (especially at the caliper end). So you get grime sitting on the seal/shaft interface

    Very old oil (eventually) goes black with the stuff pulled through the seal. Only seen it myself on a bike used for commuting in all weathers for 3 or 4 years without being bled. (Been through about a dozen sets of pads in that time.) Big glob of black fluid in the caliper, almost spotless shimano stuff in the lever.

    For “normal” mtbing, it’s pretty much a non-issue.

    hols2
    Member

    Personally, I think the advantages of DOT fluid outweigh the disadvantages, but I would happily use either. Whatever the case, you have no choice but to stick to whatever your brakes were designed for. A lot of useful information here.

    daern
    Member

    As others have said, I’ve never paid too much attention to whether a brake is DOT or mineral oil (apart from making sure the right stuff goes in!). It makes very little difference to me and as you don’t actually pour the stuff over the bike, nor drink it afterwards, I really don’t care which I use.

Viewing 38 posts - 1 through 38 (of 38 total)

The topic ‘What if I switched DOT fluid for mineral oil?’ is closed to new replies.