Can you mix hydraulic fluid with power steering?

Power Steering fluid is a hydraulic fluid and is engineered to do a specific job - it should not be mixed with anything.

General purpose hydraulic fluids are used to operate machinery that does not normally race down the highway at 100km per hour with you behind the wheel.

There are a few different power steering fluids - Dexron, Mercon, Type F; use the one that is recommended for your vehicle.