What are the consequences of mixing power steering fluids?

[VonAlejandro]

Mixing power steering fluids can accelerate oil degradation, increase mechanical wear and tear, and potentially lead to mechanical failures. Below is relevant information about power steering fluid: 1. Function: Power steering assists drivers by automatically providing steering force during turns, thereby reducing the driver's steering effort. Power steering fluid is a medium oil added to the power steering system, serving to transmit steering force and provide cushioning. 2. Replacement interval: Automobile manufacturers generally do not strictly specify the replacement cycle for power steering fluid. However, to prevent the fluid from becoming overly dirty or deteriorating, it is recommended to replace the power steering fluid every 2 years or 30,000 kilometers.

[JoannaAnn]

I used to frequently encounter cases in the repair shop where car owners mixed different brands of power steering fluid. The additives in different brands of oil can undergo chemical reactions, potentially forming sediments that clog oil passages. The power steering pump would hum noticeably louder, and the oil seals inside the steering gear would age and leak faster. The most troublesome issue is the abnormal viscosity of the mixed fluid, causing the steering wheel to jerk during rotation. Some drivers completely lost power steering assistance after just a few kilometers of driving with mixed fluids, which is extremely dangerous. Nowadays, when I see such cases, I always recommend stopping the vehicle immediately. The entire power steering system must be thoroughly flushed and refilled with new fluid, otherwise the few-hundred-dollar pump might be completely ruined.

[LaConnor]

Once a friend's car was low on power steering fluid, and he casually added transmission fluid as a substitute. The next day, the steering became extremely heavy, and the steering gear started making metallic grinding noises. Upon inspection, I found the mixed fluids had turned into a paste-like substance, clogging the valve body. The additives in different fluids have poor compatibility, and after mixing, the lubrication effectiveness drastically decreased, causing direct metal-on-metal friction. If driven under such conditions, the power steering pump bearings would wear out first, followed by gear damage, requiring a complete overhaul of the steering system. Later, just cleaning the fluid lines took three hours, and the corroded rubber hoses had to be replaced.

[Journey]

Mixing different types of power steering fluid may cause emulsification. Last week, I handled a similar malfunction where the owner mixed fluids, resulting in tofu-like sediment in the power steering reservoir. These impurities can clog the power steering filter, causing unstable oil pressure and steering wheel vibration. In severe cases, the internal valve body of the steering gear may jam, leading to sudden loss of power assistance during high-speed driving, which is extremely dangerous. Additionally, the rust prevention performance of mixed fluids deteriorates, causing metal components in the steering system to rust and generate more debris, creating a vicious cycle. It is recommended to immediately drain the mixed fluid and flush the system three times with new fluid to thoroughly clean the pipelines.