Condensed Answer: If the Campagnolo brakes in question are designed to operate with mineral oil, then one can use Shimano’s mineral oil.
That said, ideally, one should rely on the mineral oil recommended by the manufacturer to preserve the warranty of the brakes and ensure optimal performance throughout the product’s lifespan.
What is brake fluid?
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, the pressure increases and the fluid pushes the brake pads towards the brake rotor. The pads grab the rotor and slow down or stop the front/rear wheel depending on the applied force.
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 therefore 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.
In general, all hydraulic disc brakes of Shimano, Magura, Campagnolo, Clarks, Promax and Tektro use mineral oil. Meanwhile, SRAM’s brakes operate with DOT fluid except for the DB8.
(Note: In the future, the above information may change. Hence why it’s necessary to consult the documentation of the brakes that you have before proceeding with maintenance tasks.)
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
- Shimano’s mineral oil can be used with Campagnolo’s hydraulic brakes. That said, it’s recommended to stick with the oil pointed by the manufacturer because mineral oil formulas differ by brand.
- It’s not advisable to mix mineral oil from different brands. That said, people have done so without reporting major or any problems. For best practice, however, it’s wise to avoid mixing.
- At the moment, all hydraulic brakes of Campagnolo use mineral oil.
- DOT fluid should not be used with brakes designed for mineral oil because the seals could fail and lead to complete brake failure.
