At which temperatures is engine oil typically tested?

At which temperatures is engine oil typically tested?

• A. -18°C and 100°C
• B. 0°C and 60°C
• C. -30°C and 80°C
• D. -10°C and 90°C

Answer: (A)

Engine oil must perform well both when it’s very cold and when the engine is hot. Testing at a cold temperature around -18°C checks how easily the oil flows enough to be pumped and reach moving parts during a cold start. Testing at 100°C checks that, once the engine warms up, the oil stays viscous enough to form a protective film and keep bearing surfaces separated. Together, these two temperatures cover the practical ends of the operating range where lubrication matters most: startup in cold conditions and normal operation at high temperature. Other option pairs don’t target that same combination of cold-start flow and hot-running film strength, so -18°C and 100°C is the standard pairing for this concept.

Engine oil must perform well both when it’s very cold and when the engine is hot. Testing at a cold temperature around -18°C checks how easily the oil flows enough to be pumped and reach moving parts during a cold start. Testing at 100°C checks that, once the engine warms up, the oil stays viscous enough to form a protective film and keep bearing surfaces separated. Together, these two temperatures cover the practical ends of the operating range where lubrication matters most: startup in cold conditions and normal operation at high temperature. Other option pairs don’t target that same combination of cold-start flow and hot-running film strength, so -18°C and 100°C is the standard pairing for this concept.