Engine Oils
Background & Properties
castrol.com/GPS
800 255 4417
May 2025
GPS
Industry Specifications
programmed cooling rate to a final test temperature. A low torque is applied to the rotor sha to measure
yield stress and a high torque is applied to determine apparent viscosity of the oil.
API CK-4 Pass/Fail Criteria:
180-hour sample from Mack T-11 or T-11A
Viscosity @ -20° C, max: 25,000 mPA-S
Yield Stress: <35 Pa
Elastomer Compatibility Test ASTM D7216
Scope:
is seal compatibility test method evaluates the compatibility of API CK-4 oils with typical elastomeric
compounds used in heavy-duty engines. ese include nitrile, silicone, polyacrylic, and fluoroelastomers.
Test Conditions:
Test procedure: Variation of gear lube test
Test length: 20 days (336 hours)
Test temperature: 100° C for Nitrile Seals
150° C for Silicone, Polyacrylic, and Fluoroelastomer seals
Seal measurements: Volume swell
Hardness change
Tensile strength change
Elongation change
API CK-4 Pass/Fail Criteria:
Volume Hardness Tensile Elongation
Strength
Nitrile +5/-3 +7/-5 +10/-R +10/-R
Polyacrylate +5/-3 +8/-5 +18/-15 +10/-35
Fluoroelastomer +5/-2 +7/-5 +10/-R +10/-R
Silicone +R/-3 +5/-R +10/-45 +20/-30
R = TMC 1006
A11
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