High Temperature High Shear (HTHS) Viscosity Test Device

High-Temperature High Shear (HTHS), this parameter is the apparent viscosity of the lubricant fluid tested by the capillary viscosity tester at 150°C.

This test simulates the working temperature and high-speed shear of the internal combustion engine cylinder, which reflects the lubrication performance between the cylinder liner and the piston ring and the fuel economy of the lubricating oil.

SAE J300 specifies a minimum HTHS viscosity for each viscosity grade. HTHS viscosity is measured at shear 106/s and 150C.
The oil film thickness is a critical factor influencing wear, the oil film will be broken due to the positive pressure (compressive stress, non-shearing stress) between the cam and the ejector rod, between the piston and the cylinder, and between the shaft and the bearing bush.

HTHS reflects the adhesion of lubricant between the piston and the cylinder, between the shaft and the bearing bush, and is related to the oily agent or polar agent added to the lubricant. Many people call it the Oil Film Strength, which is very vivid to describe the HTST viscosity.

HTHS is an index indicating the viscosity stability of lubricating oil under high temperature and high shear, and reflects the lubricating ability of lubricating oil under high temperature and high shear conditions.