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 Corrosion Bench Test (HTCBT) ASTM D6594 Scope: HTCBT was first used by API for CG-4. is test measures a diesel engine oil's tendency to corrode various metals, specifically alloys of lead and copper, which are commonly used in cam followers and bearings. Test Conditions: Four metal specimens of copper, lead, tin and phosphor bronze are immersed in a measured amount of engine oil. e oil, at an elevated temperature, is blown with air for a period of time. When the test is completed, the copper specimen and the stressed oil are examined to detect corrosion and corrosion products, respectively. e corrosion process under investigation is believed to be induced primarily by inappropriate lubricant chemistry rather than lubricant degradation or contamination. API CK-4 Pass/Fail Criteria: Copper (Cu) 20 mg, Max Lead (Pb) 120 mg, Max Copper Discoloration 3 Max Kurt Orbahn Shear Stability Test ASTM D7109 Scope: e Kurt Orbahn test was first used by API for API CH-4. is test method covers the evaluation of the shear stability of polymer-containing fluids (e.g., multi-viscosity engine oil). It measures the percent viscosity loss at 100° C when evaluated by a diesel fuel injector apparatus procedure. e viscosity loss reflects permanent shear loss (chain breakage). Shear stability is a critical test for hydraulic/electronic unit injector (HEUI) equipped engines. Engine oils that shear down from their original viscosity cause injection pressures to drop, which decreases overall engine efficiency. Wear protection is also diminished as an oil shears. Test Conditions: Test procedure: 90 passes for both CJ-4 and CK-4 Test temperature: 100° C Test oil is sent through the test apparatus either 30 or 90 times at pressures of 1,900 to 2,600 psi, as defined by instrument calibration. e final viscosity is measured and the percent loss from the beginning viscosity is recorded. API CK-4 Pass/Fail Criteria: Kinematic Viscosity aer 90 passes: 9.3 cSt min for XW30 12.5 cSt min for 0W40 12.8 cSt min for other XW-40 grades HTHS viscosity at 150 ºC, mPa·S, min: 3.4 (XW-30 only) A9 ecastrof