The Robinair 13204 Premium High Vacuum Pump Oil, 1 Gallon Bottle is engineered to maintain maximum viscosity at high running temperatures and to improve cold weather starts. Laboratory tests prove that 13204 is more thermally stable in comparison to other leading brands, which means it resists breaking down due to heat for a longer period of time. Robinair oil has a lower moisture content than other oils, thanks to our special packaging and handling procedures. Moisture degrades the oil's purity, thinning it and reducing the pump's ability to reach a deep vacuum.