Mineral Oil Brake Fluids

Broadly speaking, hydraulic disc brakes designed for bicycles will use either a mineral oil  or an automotive DOT fluid. Genuine Shimano Mineral Oil is the only fluid compatible with Shimano brakes.

The hydraulic principles are the same, but have you ever wondered why some bicycle hydraulic brakes opt for one versus the other?

There's arguments to be made for the advantages of either type of fluid. Shimano has used both types, but our modern brakes use mineral oil.

Shimano has been making hydraulic brakes since the early 1960's and 70's, first seen in a rim brake application. At some point in the 70's the hydraulic brake system came with a caliper massive enough to probably stop a moped. The original service manual from the 70's can be viewed below, it's interesting to see how things have developed over the years.