Oils in the hydraulic power steering system: true or false

Oils in the hydraulic power steering system: true or false
09.02.2022
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Most information about power steering oil is known to car owners from the Internet. But few people think about the fact that reviews and recommendations on the Internet may be unreliable. Let's tell the truth about power steering oils!

The purpose of the oil in the power steering system is to transmit the pressure coming from the pump to the rack rod piston. The oil also provides lubrication and cooling of power steering components and prevents corrosion on metal elements.

Manufacturers offer a wide range of oils, so making the right choice can be difficult.

Types of oils for power steering

Along with the development of technology in the automotive industry, the working fluid in the power steering system has also been improved. The first fluid used in the power steering system was ATF (Automatic Transmission Fluid). The most common fluid in this class of fluids is the Dexron family of oils. ATF oils were originally used in the power steering system by Japanese car manufacturers.

European car manufacturers have developed and approved for use their own special fluid for the power steering system, which is called PSF (Power Steering Fluid). The main difference between this fluid and ATF is that the kinematic viscosity is two times lower.

For modern cars, their own fluid has been created, which has formed a new class of fluids and is called HF (Hydraulic Fluid), the names MULTIHF, Central HF can also be used. These are the most expensive, advanced and multifunctional liquids that can be used in:

  • power steering;
  • hydropneumatic suspension with the ability to adjust ground clearance;
  • anti-lock braking systems (ABS + ASR) and exchange rate stability systems (ESC);
  • hydrostatic fan drive systems;
  • electro-hydraulic drive of the convertible roof;
  • and similar systems.

The most common legends and misconceptions

1. You can distinguish the class of liquid by color: ATF - red; PSF – green; HF – yellow.

Many manufacturers of technical fluids do not comply with color coding, so it is better to focus on the markings and purpose on a specific fluid and follow the recommendations specified in the vehicle's owner's manual.
2. It is better to fill the power steering with the oil specified by the manufacturer.

This is a recommendation and it is not necessary to strictly adhere to it. You can use suitable oils from other companies.
3. Oils are allowed to be mixed; this will not cause damage to power steering parts.

Oils can only be mixed from one class and one type. Do not mix mineral oil with synthetic oil or ATF with PSF.
4. Power steering fluid requires replacement when the car has a mileage of 30-50 thousand km.

The oil change period depends on operating conditions. If the car is mainly driven around the city, then the replacement frequency is 40 thousand km. mileage If only between cities, then you can travel up to 100 thousand km. In mixed mode - no more than 60 thousand km.
5. Checking the oil is mandatory every 10-15 thousand km. mileage

This statement is correct. Regular monitoring of the oil condition will allow you to identify deviations in the system at an early stage and prevent costly repairs.
6. It is not necessary to completely change all the oil in the power steering.

This is wrong. To ensure the most trouble-free service life of the power steering system, it is necessary not only to replace all the oil, but also to replace the expansion tank, and also to flush the system of old oil and wear products.