Mostly, the car owners get the information about the oils for hydraulic power steering system from the Internet. Yet, the information they get from the reviews and recommendations may be false. Here, we’ll share the truth about the oils for HPS system.
The main task of an oil in HPS system - supplying of the pressure from the pump to the piston of steering rack bar. Besides, the oil lubricates and cools HPS assemblies and prevents the metal elements from the corrosion.
The manufacturers offer the wide range of oils which makes it sometimes difficult to choose the appropriate one.
Varieties of oils for HPS system
The more advanced vehicles become, the more advanced fluids for HPS system are produced. The first fluid that was used for HPS system - the automatic transmission fluid (ATF). The most popular fluids in this class are the Dexron standard oils. It was the Japanese automotive manufacturers who first used ATF for HPS system.
The European automotive manufacturers developed and approved the special fluid for HPS system - power steering fluid (PSF). The main difference of PSF from ATF - twice less kinematic coefficient of viscosity of PSF.
For the modern vehicles, there are fluids of a new class - hydraulic fluids (HF) that may also have the names MULTI HF, Central HF. The most expensive, advanced and multi functional, these fluids can be used for:
- hydraulic power steering system;
- hydropneumatic suspension with the clearance adjustment;
- ABS and ASR systems, and ESC system;
- fan hydrostatic drive systems;
- electric-hydraulic drive of cabrio roof;
and other systems.
The most popular ‘true or false’ statements:
No. 1. You can identify the fluids by colour: ATF – red; PSF – green; HF – yellow.
Many manufacturers of the technical fluids do not observe the colour marking. Thus, you should refer to the marking and application of the specific fluid, as well as to the recommendations specified in the vehicle user manual.
No. 2. You should fill HPS system with the oil that is specified by the manufacturer.
It’s a recommendation, and you shall not follow it. You could use the oils with the same specifications of other manufacturers.
No. 3. The fluids can be mixed. It won’t cause the damage of HPS parts.
You can mix the oils only of the same class and type. Do not mix the mineral and synthetic oils, or ATF and PSF.
No. 4. The fluids for HPS system have to be replaced once a vehicle has run 30.000-50.000 km.
The oil replacement intervals depend on the driving conditions. If you drive a car in a city, you should change the oil every driven 40.000 km. If you drive the long distances, between the cities, you can drive up to 100.000 km. For the combined mode, not longer than 60.000 km.
No. 5. You should check the oil every 10.000-15.000 km of the driven distance.
This statement is correct. The regular oil control enables the early revealing of the system malfunction; it will also prevent from the expensive repair.
No. 6. You don’t have to replace the oil in HPS system completely.
False. To enable the long proper life span of HPS system, you should not only replace all the oil but also replace the tank and flush the system to remove the old oil and wear debris.
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