Forestry machinery operates in environments where hydraulic systems are exposed to extreme temperatures, heavy loads, and constant vibrations. The efficiency of loaders, timber cranes, and logging equipment depends greatly on the hydraulic fluid, which ensures precise movement, protection against wear, and stable power transmission. Choosing the right hydraulic fluid in such conditions is not a simple formality — it is a technical necessity that directly affects the system’s performance.
One of the most important professional factors is not only the viscosity of the fluid, but also its type. For mobile hydraulics operating across a wide temperature range — such as in forestry — HV or HVLP-class hydraulic fluids are usually the right choice. These products are formulated with a high viscosity index, ensuring stable flow both in cold and hot conditions. Their properties remain consistent even with fluctuating temperatures, enabling precise manipulator movements and smooth pump operation, especially in winter, when hydraulics face the greatest challenges.
In contrast, HLP or HM-type fluids are designed for operation in stable, warm temperatures — primarily indoors, on industrial lines, or in mobile equipment that works mostly in positive outdoor temperatures. While the two fluid types may seem similar, in real conditions the differences become significant. HM/HLP fluids thicken considerably in winter, their flowability decreases, and as a result the hydraulic system becomes sluggish, responds with delay, and can place unnecessary mechanical stress on components.
Many issues operators notice in cold weather — slow manipulator start-up, uneven movements, or louder pump operation — most often occur because the wrong type of hydraulic fluid is being used in mobile machinery during the winter season.
In addition to choosing the correct fluid class, it is essential to ensure that the hydraulic fluid meets the specifications set by the pump manufacturers. Hydraulic pumps operate under high pressure and require fluid properties that provide reliable wear protection, low foaming, good filterability, and resistance to cavitation. Leading manufacturers such as Bosch Rexroth, Eaton, Denison, and others specify in their technical documentation exactly which type and specification of hydraulic fluid is required for each pump model.
Shell hydraulic fluids come with a wide range of approvals from these manufacturers, confirming that they have been tested and certified as suitable for high-load hydraulic systems. For the operator, this means an easier choice and the confidence that the selected product provides proper pump protection and predictable long-term performance.
Hydraulic fluid cleanliness is no less important. Forestry machinery operates in an environment with a particularly high risk of contamination, meaning that any impurities — dust, moisture, metal particles — can accelerate wear on valves and pumps. Maintaining the correct cleanliness class and replacing filters on time is essential to ensure that the benefits of the hydraulic fluid are not lost due to contamination.
A high-quality hydraulic fluid for forestry machinery is not just a consumable — it is an integral part of the system that determines efficiency, safety, and overall operating costs. The right fluid type, proper viscosity, compliance with manufacturer specifications, and strict cleanliness control together ensure that loaders and timber trucks operate reliably throughout the entire season. Shell Tellus hydraulic fluids — especially Tellus S2 VX 46 — are designed specifically for these conditions and are a reliable choice for operators who need smooth and predictable hydraulic system performance, even in the harshest working environments.
