- What if I switched DOT fluid for mineral oil?
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?Posted 2 years agoP-JayMember
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).Posted 2 years ago
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.Posted 2 years agoYakSubscriber
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.Posted 2 years agoellipticMember
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…Posted 2 years agostevextcMember
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.Posted 2 years ago
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.Posted 2 years agoYakSubscriber
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..Posted 2 years ago
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.Posted 2 years agopatonMember
…and then there is brake pad dust and tyre dust that can be inhaled.Posted 2 years ago
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.Posted 2 years agodeadkennyMember
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.Posted 2 years agoStevet1Member
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?Posted 2 years ago
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.Posted 2 years ago
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.Posted 2 years agodaernMember
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.Posted 2 years ago
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