I am sure no one has because mineral oil is not compatible with any SRAM brake. You have to us DOT brake fluid, no way around that. The only reason anyone would want to do that is if they wanted to destroy their brakes and buy new ones.
Thanks for pointing out the obvious. Don't be so naive, loads of people Have run breaks on water when in a pinch. Dot fluid is corrosive so will definitely damage seals designed for mineral oils, but I've never had a definite answer on the other way round, so someone with experience would be nice. Personally I don't want to use dot fluid.
I'm probably going to buy some cura 4's as the lever throw is to long on the srams with topping up the main cylinder mid pad life for me, but if I can get away with mineral oil in the guide r's then happy days.
with brake systems the only answer is use what the manufacturer says to use
it is critical safety equipment. deviate and you are now in untested and unsupported config and if your brakes fail as a result, and at a critical moment...[what happens?]
I'll use the other break to stop thanks. Plus I'll see them weeping oil and they be spongy as a damp sponge. It's not like we're landing rockets on a barge here...
Well these guys did it and it didn't seem to go well. OP wasn't being naive with my answer just using common sense. Oh and using water in a pinch. Well moisture or water is not the same as using a completely different type of fluid. Plus the DOT brakes (not breaks by the way) are exposed to water all the time. Brake fluid is hudroscopic. That is why you should t use old brake fluid that is sitting around. It lowers the boiling point of the brake fluid and can cause brake fade. Much more of an issue for cars though.
Why do you want to run mineral oil? Less corrosive...
If you are complaining about lever throw it will worsen w/ mineral oil. From SRAM tech document:
"DOT fluid is less compressible than mineral oil. DOT was specifically invented to be incompressible-a key attribute of any high-performance hydraulic fluid"
DOT is fine and in many ways superior to mineral oil, which is why it's used in cars, trucks, motos, etc... I started dealing with it doing the brakes on my beater cars in the mid '70s and since in cars, motos and later bicycles. It's not corrosive (whatever you might mean by that) and is certainly no big deal. Get over it.
All above points aside, SRAM brakes are well known for their warranty issues. More than any other product I've dealt with over the years, I've sent SRAM brakes in for replacement way to often. Using anything beside DOT fluid will void the warranty.
Why would you want to do this in a non-emergency situation?
And what could possibly cause an emergency situation where you've got all the equipment to bleed the brakes, but not DOT fluid, a thing you can get at most every gas station, hardware store, and auto parts supplier?
As far as DOT fluid being less compressible than mineral oil... they're both liquids and incompressible by nature. The DOT may entrain less air, it may have a higher boiling point, it may expand less when warm, but less compressible? I'm not buying that claim.
Putting mineral oil in a system designed for DOT fluid is a recipe for failure and expensive reconstructive surgery.
However I have a dim recollection of SRAM announcing a line of mineral oil brakes for the Euro market around 2014-15 because DOT fluid is more strictly regulated in the EU.
I bleed my brakes underwater to save money. One time my front brake got a flesh-eating bacteria in the caliper and the darn thing kept messing up the bite point.
Most likely the seals will be the only problem, they will fail if brake fluid is different than what the seals are designed for. The cylinders and pistons will likely be just fine. So technically if you would replace the seals with some other type which can cope with mineral oil, the system should work just fine.
The seals will most probably withstand water just fine, so using water technically works with no problems. The problem however will be low boiling point and corrosion...
Most likely the seals will be the only problem, they will fail if brake fluid is different than what the seals are designed for. The cylinders and pistons will likely be just fine. So technically if you would replace the seals with some other type which can cope with mineral oil, the system should work just fine.
The seals will most probably withstand water just fine, so using water technically works with no problems. The problem however will be low boiling point and corrosion...
Seal concerns aside. Mineral oil is thicker and will make the action slow.
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