Condensed answer: While both Shimano and Magura brakes rely on mineral oil, the formulas used by the companies are different. To preserve the warranty of the brakes and reduce the chances of unexpected problems, it’s highly recommended to stick with the mineral oil type suggested by the brake manufacturer.
Brake Fluid Types
Hydraulic disc brakes control the movement of the pistons and brake pads via brake fluid running in the brake cables.
When the rider squeezes the brake lever, the pressure increases and the fluid pushes the brake pads towards the brake rotor. When the rider releases the lever, the pressure decreases. Then, the fluid “backs off” and frees the rotor.
Mineral Oil and DOT Fluid
The two most common types of bicycle brake fluids are mineral oil and DOT fluid.
DOT fluid is the most used brake fluid because it also appears in the automotive industry. DOT fluid undergoes strict regulations by the Society of Automotive Engineers and the Department of Transportation. (Note: DOT means Department of Transportation).
Mineral oil, on the other hand, is not regulated. Hence why all producers have a proprietary formula kept in high secrecy. For that reason, it’s recommended to use the oil that the brake manufacturer suggests.
That said, at the end of the day, mineral oil is still mineral oil regardless of the brand and can often be used even when the brakes’ manufacturer is different from the mineral oil producer.
However, it’s absolutely crucial to NEVER use DOT fluid instead of mineral oil and vice versa to avoid brake failure.
In other words, always use mineral oil for mineral oil brakes and DOT fluid for DOT fluid brakes.
Is it ok to mix mineral oils from different brands?
The standard answer is no for the following reasons:
- You will lose the warranty on the brakes as you are not following the instructions of the manufacturer.
- There are no standards for mineral oil. Consequently, producers rely on slightly different formulas. One cannot know with 100% certainty how the substances in each formula will react when exposed to those from another brand.
- The seals found in the calipers of hydraulic brakes are designed and tested to operate with the specific fluid of the brake manufacturer. Thus, there’s a chance that the seals will experience damage when mineral oil from another brand is used.
Real World Experience
Even though the rules suggest that one should respect the recommendations of the manufacturers, people have been mixing mineral oil from different brands without reporting adverse reactions.
For example, in some cases, people resort to Shimano’s mineral oil for other mineral oil brakes (e.g., Magura, Tektro…etc.) simply because the recommended mineral oil type is hard to find locally. This is not proper practice, strictly speaking, but it would be inaccurate to conclude that it doesn’t work.
FAQ: What about using Magura oil in Shimano brakes?
In this case, we observe the same phenomenon – it’s technically not recommended and some people say that the combination will damage the brakes’ seals, but there’s also evidence suggesting that the mix is acceptable.
The video below contains such an experiment and concluded that it’s fine to mix mineral oils from different brands:
FAQ: What are the advantages and disadvantages of hydraulic brakes in comparison to mechanical units?
Hydraulic disc brakes have the following advantages:
- Self-centering (you don’t have to play with the pads to prevent rubbing)
- Stronger “squeeze” for the same effort (Hydraulic brakes make it possible to stop with 1-2 fingers because the levers do not have to be squeezed as hard.)
The downside of hydraulic disc brakes is that they require more sophisticated maintenance (bleeding) and cannot be repaired in the wild. Once the fluid is lost, the brake no longer works. Hence why people who want a simple setup that just works often stick with mechanical models.
Summary: What You Need To Know
- To be on the safe side and preserve the warranty offered by the brake manufacturer, only use the recommended fluid for the specific brake model.
- The most important part to remember is to never mix DOT fluid and mineral oil. Use DOT fluid for DOT fluid brakes and mineral oil for mineral oil brakes. Otherwise, the seals will definitely leak and cause brake failure.
- Even though it’s not recommended to use third-party mineral oil, people have been mixing mineral oils from different brands with normal results.
- The difference between mineral oils isn’t huge even though there are no strict regulations. The basic formula is similar. It’s logical for the manufacturers to only recommend the fluids that their brakes have been tested with. This method minimizes the risk of brake failure and improves the commercial stats of the company.