DOT vs mineral oil
They're the two brake fluids, and they're chemically incompatible. DOT (glycol-based) is used by SRAM, Hayes and Hope: it's hygroscopic (absorbs water, changed often), handles more heat (≈230–260 °C) and is corrosive. Mineral oil (petroleum-based) is used by Shimano, Magura and Tektro: it's hydrophobic (repels water), non-corrosive and long-lived, but with a lower boiling point. The critical point: mixing or swapping them destroys the seals in hours. Each brake uses only its own.
It's the costliest and easiest brake mistake: putting in the wrong fluid. Here's how to know which is yours and why they never mix.
Why they're incompatible
DOT and mineral are different chemistries: DOT's base dissolves the rubber seals designed for mineral, and conversely mineral swells DOT's seals. Either way the result is leakage and total brake failure within hours. So it's not about brand or preference: your brake is designed for one, and only that. The functional difference: DOT disperses water (spreads it) and mineral isolates it (it pools in the caliper).
Head to head
How to know which is yours
The reservoir cap or brake manual says it: «DOT» or «Mineral». If it's SRAM, almost certainly DOT; if Shimano, mineral. Never top up or bleed with the other fluid, not even «just once». And within DOT, 4 and 5.1 are compatible with each other; DOT 5 (silicone) isn't for bikes.
If you don't know which mount, rotor or fluid your brake uses, send us the case. Real diagnosis, nothing to sell you. Message us on WhatsApp
Frequently asked questions
How do I know if my brake uses DOT or mineral?
The reservoir cap or manual says it. As a rule: SRAM/Hayes/Hope use DOT; Shimano/Magura/Tektro use mineral oil. Never swap them.
What happens if I mix DOT and mineral?
Catastrophic failure: the wrong fluid destroys the brake's rubber seals and causes leaks and total brake loss within a few hours.
Which is better, DOT or mineral?
Neither is «better»: DOT handles more heat but absorbs water and is corrosive; mineral is friendlier but boils sooner. Use what your brake requires.