Petroleum-based or mineral-based fluids are the most widely used hydraulic fluids today due to their good lubrication properties. Water-based fluids provide fire resistance but require careful monitoring to prevent problems from changes in viscosity or compatibility issues. Synthetic fluids offer advantages like fire resistance and thermal stability but are typically more expensive and potentially toxic. Hydraulic fluids are used for tasks like pressure transfer, lubrication, cooling, cushioning oscillations, corrosion protection and signal transmission in hydraulic systems.