In the 1920s, hydraulic systems had a frustrating problem: oils became syrupy in cold weather and dangerously thin when hot. Dean and Davis at the National Bureau of Standards invented the Viscosity Index (VI) scale to quantify this behavior. Standard mineral oils scored 95-100 VI, but engineers dreamed of better.
The breakthrough came with High Viscosity Index (HVI) oils, using special refining processes and additives to achieve VI ratings of 140 or higher. This meant hydraulic systems could operate reliably from Arctic winters to desert summers without viscosity-related failures. The technology transformed everything from construction equipment to manufacturing machinery.
The difference is dramatic: a conventional oil might thicken 10 times from summer to winter temperatures, while HVI formulations maintain remarkably stable flow characteristics across that same range.
Modern formulations like HYDRAULIC OIL HV 22 continue this tradition, delivering HVI performance for heavy-duty hydraulic systems operating in variable conditions.
