Issue link: http://read.dmtmag.com/i/859318
Engine Oils Background & Properties castrol.com/GPS 800 255 4417 May 2025 GPS Industry Specifications High Temperature High Shear (HTHS) Viscosity Test ASTM D4683 Scope: e HTHS test gives an indication of temporary shear stability of the viscosity index improver used in multi- grade oils. Test Conditions: Unlike Kinematic Viscosity, HTHS viscosity is measured under conditions similar to those of an operating engine. e test is conducted at 150° C under shear stress conditions similar to those found in very thin film lubrication areas. An example is the piston ring-to-cylinder wall interface. e value obtained from this test provides an indication of the ability of the oil to maintain fluid film strength in an engine. API CK-4 Pass/Fail Criteria: Non-Critical Limit: 3.5 cP min API FA-4 Pass/Fail Criteria: Non-Critical Limit: 2.9 - 3.2 cSt Foaming ASTM D892 is test is the standard test method for foaming characteristics of lubricating oils. Scope: e tendency of oils to foam can be a serious problem in systems such as high-speed gearing, high-volume pumping, and splash lubrication. Inadequate lubrication and cavitation can lead to component failure. is test method is used in the evaluation of oils for such operating conditions. Test Conditions: e sample, maintained at a temperature of 24° C (75° F), is blown with air at a constant rate for 5 minutes and then allowed to settle for 10 minutes. e volume of foam is measured at the end of both periods. e test is repeated on a second sample at 93.5° C (200° F), and then, aer collapsing the foam, at 24° C (75° F). API CK-4 Pass/Fail Criteria: Sequence I: 10 minutes/ 0 max Sequence II: 20 minutes/ 0 max Sequence III: 10 minutes/ 0 max Sooted Oil Mini-Rotary Viscometer (MRV) ASTM D6896 Scope: is test utilizes an MRV that consists of one or more viscometric cells in a temperature-controlled aluminum block. Each cell contains a calibrated rotor-stator set. e rotation is achieved by applied load acting through a specified pulley mechanism. Test Conditions: A used engine oil sample is heated at 80° C and then vigorously agitated. e sample is then cooled at a A10 ecastrof