Viscosity @ 40°C or 100°C

Definition

Viscosity measures a lubricant's resistance to flow (fluid thickness) at temperature and is considered an oil's most important physical property. Depending on lube grade, viscosity is tested at 40 and/or 100° Celsius.

Standard Test Method Used

mod. ASTM D445

Reporting Measurement

cSt (Centistokes)

Amount of Sample Needed

2 mL

Test Limitation

Accuracy diminishes with lubricants above ISO 1000 grade.