Heat Transfer Oils are high-performance fluids specially designed for use in enclosed, indirect heating systems. They are meticulously crafted from exceptionally refined base stocks known for their resistance to thermal cracking and chemical oxidation.

These oils boast efficient heat transfer capabilities and exhibit viscosities that allow for easy pumping, both during startup and while operating at temperature. Importantly, the flash point of these fluids remains stable throughout their service life, thanks to their resilience against thermal cracking at recommended operating temperatures.

Heat Transfer Oils are exceptionally thermally stable, ensuring an extended service life without the formation of deposits or viscosity increase. They feature specific heat and thermal conductivity properties that enable rapid dissipation of heat.

These versatile oils can be employed in various industrial processes, including open, cold-oil sealed, and indirect heating and cooling systems. They consistently deliver excellent performance, as demonstrated by their impressive GM Quenchometer (ASTM D-3520) results.


Heat Transfer Oils can be used in open installations where fuming of the oil could be a problem. Specific application ranges and advice are (temperature range for bulk fluids):

  • Closed systems: up to 300oC
  • Open systems: up to 160°C


Ideally Heat Transfer Oils should not be mixed with other oils since this may impair the excellent thermal and oxidation stability of the Heat Transfer Oils and may cause changes in other properties; thus complicating the interpretation of analyses made to determine the fluid’s useful life.

If the fluid is used above the recommended maximum temperatures, vapor lock may result unless the system is designed to operate at the higher temperature by pressurizing with an inert gas such as nitrogen. However, at higher temperatures, fluid life will be shortened because the rate of thermal degradation increases markedly as temperatures rise above the recommended limit.

In well-designed systems the temperature of the oil film surrounding the heating element should be about 15oC to 30oC above the bulk oil temperature. If higher than this, the service life of the fluid may be shortened and sludge and coke may be deposited, which would interfere with the heat transfer rates.

As with other mineral oils, Heat Transfer Oils should be used only in systems with forced circulation. Systems that depend on convection for circulation of the heat transfer medium do not provide a rapid enough flow to prevent local overheating, resulting in a rapid deterioration of the fluid.

Further, these fluids are not recommended for use in open systems where hot fluid is exposed directly to the air. If hot fluid sprays or escapes from leakage points, it may spontaneously ignite.

Vesta suggests that the equipment manufacturers’ recommendations for viscosity grade, performance requirements and general operating conditions should be checked prior to use.


PropertyUnitsASTM Method  Typical Results 
ISO Viscosity122125326890
Code VI6-287228762877287328802874
Density @ 15°Ckg / LD-1298834850858871873879
Viscosity @ 40°CcStD-445122125326890
Viscosity @ 100°CcStD-44534.
Flash Point°C200200200220250260
Spontaneous Ignition Temperature  °C   >400  >400  >400  >400  >400  >400
Recommended Temperature Maximum  °C   250  300  300  300  300  300

Available in:          Bulk, 1000 Litres, 200 Litres and 20 Litres.

Item Code:              VI6-2872 (12), VI6-2876 (21), VI6-2877 (25), VI6-2873 (32), VI6-2880 (68), VI6-2874 (90)

Product Informations

Product Data Sheet

Material Safety Data Sheet