Yes, hydraulic fluid can be flammable, but its flammability depends on the type of fluid used. Hydraulic fluids generally fall into three categories based on their fire resistance: Petroleum-Based Hydraulic Fluids – These are the most common and are flammable because they contain mineral oil. If exposed to an ignition source, especially under high pressure, they can catch fire and ... https://whyps.com/is-hydraulic-fluid-flammable