Is it better to have higher or lower engine oil viscosity?

[StCarlos]

Engine oil viscosity should be neither too high nor too low. If the oil viscosity is too high, it will increase the operating resistance inside the engine, leading to reduced engine power and increased fuel consumption. If the oil viscosity is too low, the oil cannot form a stable oil film, which will aggravate engine wear. Oil viscosity changes with temperature, so special attention should be paid to its performance under both low and high temperature conditions. For example, in 5W-30, the first number indicates low-temperature fluidity. 5W means it can withstand low temperatures of -30°C. The smaller this number, the better the low-temperature fluidity, making cold starts smoother in winter. The latter number represents the kinematic viscosity at 100°C. A higher value indicates better ability to maintain viscosity at high temperatures, which can also be understood as better lubrication performance under high-temperature conditions. When selecting engine oil, please note the following: Choose oil according to the engine manufacturer's specifications. There's no need to use overly advanced oil in engines with lower requirements, nor should you use lower-grade oil in engines with higher requirements. Multi-grade oil is recommended because it is economical, long-lasting, and efficient, providing better protection for the engine. Due to the characteristics of multi-grade oil, it may appear darker than normal and have slightly lower oil pressure during use - both are normal phenomena.

[SanAdriel]

With over 20 years of driving experience, I've gained some insights about oil viscosity. High-viscosity oils like 10W-40 have slower cold starts in winter, but provide more stable engine operation in summer with reduced noise and better protection. Low-viscosity oils such as 0W-20 offer easier cold-weather starts and slightly better fuel economy, but may lack sufficient wear resistance for older vehicles. The key is considering both vehicle condition and season: new cars typically recommend low-viscosity oils for fuel efficiency and environmental benefits, while older vehicles in hot climates benefit from higher viscosity. I never make arbitrary choices - always consulting the maintenance manual, as incorrect selection may lead to engine wear or oil consumption. When changing oil, I suggest consulting a repair shop to test engine condition, maintaining 5,000-km inspection intervals, and avoiding random brand switches just to save money.

[VanRuby]

I drive a fuel-efficient compact car for my daily commute in the city with frequent traffic jams, and I've found that using lower viscosity engine oil does help reduce fuel consumption. For example, 5W-30 oil allows quicker engine starts and makes short-distance driving easier, saving quite a bit on fuel costs. In contrast, higher viscosity oils like 10W-40 require longer warm-up times in winter and consume more fuel. But it's not a one-size-fits-all solution: driving habits matter – if you frequently drive at high speeds or your car is over ten years old, slightly higher viscosity provides more reliable engine protection. I often adjust based on weather and mileage – using higher viscosity in high temperatures and lower in cold conditions. Ultimately, it's best to get an annual oil quality check during maintenance. Don't just focus on viscosity while neglecting regular oil change intervals – this approach extends engine life.

[MacMargaret]

I live in a cold northern region and have experienced the trouble of excessively high oil viscosity in winter. Low viscosity oils like 0W-20 allow quick cold starts and can start the engine even at -20°C; whereas high viscosity oils, such as 15W-50, make winter starts difficult and drain the battery faster. High viscosity performs slightly better in summer, but overall I recommend following the vehicle manual—newer cars typically use low-viscosity oils for better fuel efficiency and compatibility with modern engines; older vehicles may appropriately increase viscosity to protect internal components. Remember to check the oil grade before seasonal changes and avoid mixing oils of different viscosities. Regular maintenance can also prevent issues.

[Esther]

Engine oil viscosity depends on too many factors, but I believe the core is engine protection. Higher viscosity like 10W-40 reduces wear during high-temperature or high-load driving, such as hill climbing or long-distance trips, with thicker oil film preventing overheating. Lower viscosity oils like 5W-30 suit urban commuting, being fuel-efficient but prone to thinning at high temperatures. My recommendation is to choose based on vehicle age and climate: older vehicles in hot regions benefit from higher viscosity; newer cars or cold climates should use lower viscosity. Never overlook driving conditions - incorrect viscosity may cause unstable oil pressure or smoke. Regularly check oil level and color, changing every six months to ensure performance.

[StElias]

As a car enthusiast, I've tested the performance impact of different oil viscosities. Low viscosity oils like 0W-20 provide quicker acceleration, responsive engine performance, and better fuel efficiency, but they heat up faster during aggressive driving and offer slightly less protection. Higher viscosity oils such as 5W-40 deliver stronger protection and better high-temperature resistance, making them ideal for modified cars or older engines. There's no absolute best choice – it depends on your vehicle type and usage scenario: daily drivers should stick to manufacturer-recommended low viscosity, while sports cars can moderately increase viscosity. Remember, basic maintenance is crucial – choosing the right viscosity with poor oil quality is pointless. Change oil filters regularly to keep the engine clean and extend its lifespan.