What does the 'W' in motor oil represent?

[BrantleyFitz]

In motor oil, the 'W' stands for 'Winter', indicating that the oil can be used normally during winter. Common oil grades include 5W30, 5W40, 0W30, and 0W40. The number before the 'W' represents the oil's low-temperature flow performance: 5W means the oil can flow normally at -30°C, while 0W means it can flow normally at -35°C. The number after the 'W' indicates the oil's high-temperature viscosity, with higher numbers representing higher viscosity. Motor oil, also known as engine lubricating oil, consists of: 1. Base oil: the main component of lubricating oil, determining its basic properties; 2. Additives: these compensate for and improve any deficiencies in the base oil's performance.

[AsherFitz]

That day at the garage, the veteran mechanic mentioned that this 'W' is actually the first letter of the English word 'Winter'. The 'W' in the 5W-30 on the engine oil bottle indicates its low-temperature fluidity test standard. For example, 5W means it can maintain normal pumping at -30 degrees Celsius, and the smaller the number, the better the low-temperature fluidity. Nowadays, if a car has trouble starting in winter, it's mostly because the W value is too high. The number 30 after it represents the high-temperature viscosity, which is crucial for summer highway driving. In our northeastern region, we generally use 0W or 5W, while 10W is sufficient in the south. Last time, a neighbor's car wouldn't start in winter, but after switching to 0W oil, it started right up. Remember, choosing oil with the GF-6A mark is the most reliable.

[StHarrison]

Last month, I helped my dad change the engine oil for his car and specifically researched this W rating. The mechanic pointed at the oil can and said, the smaller the number before the W, the smoother the cold start. For example, my old Jetta uses 5W-40, and it starts right up even at minus ten degrees in winter. However, the mechanic reminded me not to blindly chase low viscosity for older cars, as it might lead to oil burning. There was an eight-year-old SUV in their workshop using 0W-20, and it needed half a liter of oil every two thousand kilometers. Now, when changing oil for the three cars at home, I always remember: for new cars, follow the manual; for older cars, appropriately increase the high-temperature viscosity value, such as going from 30 to 40.

[StDominic]

Simply put, W stands for Winter, which relates to the low-temperature performance of engine oil. Numbers like 0W, 5W, and 10W marked on the bottle indicate the oil's cold resistance—the smaller the number, the better the freeze resistance. For example, 0W can flow at -35°C, while 10W can only handle down to -25°C. Once during a road trip in Mohe, a companion's car using 10W oil turned into paste in the morning due to the cold. It's recommended that drivers in northern regions choose at least a 5W grade, while those in the south can use 10W. Additionally, the high-temperature viscosity number (following the W) must match the engine's requirements. German cars typically use 40 viscosity, while Japanese cars often use 20. Nowadays, most new full-synthetic oils come with dual certification labels.

[CoreyAnn]

The 'W' in motor oil grades stands for winter suitability. For example, in the common 5W-30, the smaller the number before W, the better the low-temperature fluidity. Last week when helping my cousin choose oil, we encountered this - his newly purchased hybrid requires 0W-16. This ultra-low viscosity oil enables quick cold starts and reduces engine wear during warm-up. The mechanic mentioned that with modern oil formulations, 0W oil can still pump at -40°C. But viscosity selection is crucial - my old BMW's manual specifies 5W-40, and once a shop mistakenly used 5W-30, triggering the oil pressure warning light during highway driving.

[JulianaAnn]

The W-rating of engine oil affects vehicle operating costs. Our fleet conducted tests: after switching from 10W-40 to 5W-30, fuel consumption decreased by 0.4 liters per 100 km. The truck fleet leader mentioned that a difference of 5 viscosity grades can reduce winter startup time by two seconds. However, don't just focus on W-ratings for fuel savings. Last year, some drivers bought cheap 10W oil, resulting in abnormal wear of transmission synchronizers. Now I always look for ACEA A3B4 or API SP certification marks. A reminder for friends in southern regions: pay attention to high-temperature viscosity values during summer long-distance trips - 30 or 40 grades are recommended. For northern winters, 0W or 5W is safest, especially for turbocharged vehicles.