The differences between ATF, PSF and HF steering fluids, and which popular beliefs about colour coding, mixing and change intervals actually hold true.
Power steering fluid transmits pump pressure to the rack piston while also lubricating, cooling and protecting components against corrosion. MSG Equipment notes that online advice is not always reliable and explains the three main classes: ATF (the Dexron family), the European PSF with roughly half the viscosity, and HF fluids used across several hydraulic systems in modern cars.
- Colour does not identify the class; follow the label and the owner’s manual.
- Only fluids of the same class and type may be mixed — never mineral with synthetic or ATF with PSF.
- Change intervals depend on driving conditions, while regular level checks are essential.