What Does Engine Oil Viscosity Mean?
2 Answers
Engine oil viscosity is a measure of the thickness of a liquid or its resistance to flow. Engine oil, also known as engine lubricant, consists of: 1. Base oil: The main component of lubricating oil, determining its fundamental properties; 2. Additives: These compensate for and improve deficiencies in the base oil's performance. The effects of excessively low engine oil viscosity include: 1. Poor engine lubrication, increasing wear on piston rings and cylinder walls, reducing sealing performance, leading to oil burning; 2. Poor sealing performance of valve seals and damage to the crankcase forced ventilation valve; 3. Blockage of the crankcase ventilation port, causing excessive pressure inside the crankcase; 4. Inability of the oil to form a stable oil film on the surfaces of various engine components, resulting in the sudden generation of a large amount of heat within the engine.
Oil viscosity can be simply understood as the thickness of the oil, much like syrup—the thicker it is, the harder it flows. Based on my years of experience, viscosity is indicated by SAE numbers on oil labels, such as 5W-30. The number before the 'W' represents cold-weather performance—the lower the number, the easier the oil flows in winter, providing faster engine protection during cold starts. The number after indicates viscosity at high temperatures—the higher the number, the thicker the oil, forming a stronger protective film to prevent wear when the engine is hot. This is crucial—choosing the wrong viscosity can accelerate engine wear or cause starting difficulties. I must remind you that temperature makes a big difference: using oil with a high 'W' value in cold weather slows oil flow, leading to dry friction between parts, while oil that's too thin in hot weather offers insufficient protection. I always follow the car manual's recommendations—don’t switch randomly, as it also affects fuel efficiency. The right viscosity can save you some money on gas. In short, check your oil regularly, and replace it when viscosity degrades to avoid engine trouble.
