What does fully synthetic engine oil 0w40 mean?

[CoraDella]

The meaning of engine oil 0w40 is as follows: 1. The 0W in 0W-40 indicates the cold-start performance of the engine oil. Using engine oil with a lower number before the W makes it easier to start the engine in cold weather. 2. The 40 in 0W-40 represents the viscosity characteristics of the engine oil at high temperatures. High-viscosity engine oil (with a higher value) may be more suitable for vehicles driving at high speeds or carrying heavy loads. 3. If the engine oil viscosity is higher, the sealing performance is better, but the engine will consume more fuel. At idle, higher viscosity engine oil results in lower noise, while at driving speeds, higher viscosity engine oil produces higher noise. Lower viscosity engine oil, on the other hand, has the characteristic of being more fuel-efficient.

[StBentley]

Wow, the string of numbers '0w40' looks like a code, doesn't it? Let me break it down. First, '0w' represents low-temperature fluidity, with 'W' standing for 'winter'. That '0' is impressive—it can keep flowing smoothly through engine gaps even at -40°C, providing excellent cold-start protection. The '40' refers to high-temperature viscosity, meaning it can maintain oil film thickness even when the engine is scorching hot. 'Full synthetic' indicates artificially synthesized base oil, which is purer and more durable than mineral oil, with strong resistance to high-temperature degradation. It's especially suitable for German cars or vehicles that frequently drive on highways. I use this grade in my car, and I feel the throttle response is much sharper.

[FernandoLynn]

As a veteran driver with 20 years of experience, I fully understand the charm of 0w40 full synthetic engine oil. The 0w represents its performance in extreme cold, flowing smoothly even at -35°C; the 40 indicates its viscosity grade when the engine reaches 100°C. The molecular structure of full synthetic oil is uniform, making it less prone to cracking at high temperatures and reducing sludge buildup. Last winter at -30°C, my car started successfully on the first try while others struggled. However, it's important to note that Japanese and Korean cars may be better suited for 20 or 30 viscosity oils, so don't blindly chase higher viscosity.

[ElleFitz]

When buying engine oil, just focus on the three key indicators of 0W40. The first digit '0' represents the low-temperature fluidity grade - the smaller the number, the better the cold resistance (subtract 35 from the W number to get the minimum operating temperature: 0-35=-35°C). The '40' after W belongs to the SAE high-temperature viscosity standard - the higher the number, the stronger the high-temperature protection. Full synthetic oil has high purity and can last up to 10,000 km between changes. Last maintenance, the mechanic said my car runs much quieter with 0W40, even valve noise reduced significantly, and there's no worry about oil film tearing at high RPMs.