What is the method for determining oil viscosity?
2 Answers
The method for determining oil viscosity is: The oil viscosity grade is indicated on the oil bottle. SAE represents the viscosity grade of the oil. The number before 'W' indicates the winter viscosity, with a smaller number indicating lower viscosity. The number after 'W' indicates the summer viscosity, with a larger number indicating higher viscosity. The functions of engine oil are: 1. Lubricating between pistons and cylinders, main shafts and bearing bushes; 2. Carrying heat back to the oil tank and then dissipating it into the air to help the radiator cool the engine; 3. Transporting carbon deposits, sludge, and worn metal particles from engine parts back to the oil tank through circulation, cleaning dirt generated on the working surfaces of parts; 4. Forming a sealing ring between piston rings and pistons to reduce gas leakage and prevent external contaminants from entering; 5. Preventing rust and corrosion; 6. Buffering the load on pistons, piston chips, connecting rods, and crankshaft bearings; 7. Reducing the friction coefficient.
As a seasoned veteran who has worked in auto repair shops for years, determining oil viscosity isn't actually difficult. I often use the finger rub method: pull out the dipstick, drop some oil on your fingers and rub it a few times; if the oil flows as easily as water, it's generally too thin, indicating possible degradation or deterioration. For a more professional approach, we use a viscometer test - placing the oil in the instrument to observe its flow rate, which gives precise viscosity index numbers. Don't forget to check the color - fresh oil is a clear yellowish-brown, while old or contaminated oil turns black and thin. Temperature has significant impact - oil thickens in cold weather and thins in heat, which is why SAE grades like 5W-30 are designed to accommodate seasonal changes. When inspecting, pay attention to the oil film thickness on the dipstick; low viscosity can lead to insufficient lubrication, increased engine wear, or even overheating failures. I recommend checking every 5,000 kilometers - don't wait until the warning light comes on to panic. Developing this habit can extend engine life, saving money and giving peace of mind.
