How are motor oil grades ranked?
1 Answers
Motor oil grades are ranked from SA up to SN. With each increasing letter, the performance of the oil improves over the previous grade, and the further back the letter is in the alphabet, the higher the quality grade. The functions of motor oil are: 1. To separate the surfaces of relatively sliding parts, thereby reducing wear; 2. To carry heat back to the oil tank and then dissipate it into the air, helping the radiator cool the engine; 3. To circulate carbon deposits, sludge, and worn metal particles from engine parts back to the oil tank, flushing away dirt generated on the working surfaces of parts through the flow of the lubricating oil. The effects of using inferior quality oil are: gum and incompletely burned substances can accumulate on the valves, intake passages, and combustion chambers, affecting engine performance and causing engine damage.