Is a Higher Motor Oil Grade Always Better?

[LeJohnny]

Motor oil grade is not necessarily better when higher. The selection of engine oil should be based on the vehicle's operating environment temperature, engine working temperature, workload, and design assembly parameters, rather than blindly opting for higher-grade oil. Motor oil, engine oil, or engine lubricant is a substance enhanced with additives in base oil, primarily containing anti-wear additives, detergents, dispersants, and multi-grade oil viscosity index improvers. Motor oil is used for lubricating internal combustion engines, with its main functions being to reduce friction and wear of moving parts, as well as to remove sludge and varnish from the engine.

[McLouis]

I used to think the higher the oil grade, the better. But after using high-grade oil in my old car, the engine noise increased and fuel consumption soared. Grades like 5W-30 or 10W-40 represent viscosity and temperature characteristics. Higher numbers mean thicker oil, making cold starts difficult in winter and increasing resistance in summer. This doesn't protect the engine; instead, it may wear out components. My experience is to follow the car manual's recommendations. New cars generally use low viscosity like 0W-20, while older cars can use slightly higher grades, but don't change arbitrarily. Regular oil changes every 8,000 kilometers are far more important than the grade, keeping the engine smooth and saving money.

[AbelAnn]

During car repairs, I've noticed many people mistakenly believe that higher oil viscosity ratings are always better. The rating such as 5W-30: the first number (e.g. 5W) indicates cold temperature fluidity - the lower this number, the smoother cold starts; the second number (e.g. 30) represents high-temperature viscosity. Engine designs have specific requirements - using excessively high viscosity (e.g. 10W-50) can strain the oil pump, increase fuel consumption, and reduce efficiency. Manufacturers recommend viscosity grades based on testing, so I advise owners to check their manuals rather than guessing. Minor seasonal adjustments are acceptable (lower viscosity in winter), but stay close to the recommended range overall.

[DeElizabeth]

Having driven for many years, I've tried everything from gasoline to diesel. Higher oil grades aren't necessarily better - like when I used high-grade oil and my car started as slow as a snail in winter. Engines need proper viscosity protection; too high viscosity increases resistance and fuel consumption, while too low risks wear. Always choose according to the manual - new car models often require low viscosity like 5W-20, don't try to save money by making your own decisions. Maintenance intervals are more crucial than oil grades, check oil quality every 7,000 kilometers.