Is High or Low Engine Oil Viscosity Better?
2 Answers
There is no definitive answer as to whether high or low engine oil viscosity is better. More information about engine oil viscosity is as follows: 1. Higher oil viscosity leads to higher fuel consumption in the engine. At idle, higher viscosity oil results in lower noise; while driving, higher viscosity oil produces more noise. Lower viscosity oil, on the other hand, has the characteristic of saving fuel. 2. The viscosity of the oil should be selected based on the engine's condition and the ambient temperature. If the internal parts of the engine have small clearances, lower viscosity oil is needed; if the clearances are large, higher viscosity oil is required. 3. New engines with minimal internal part wear and small clearances require lower viscosity oil, while older engines need higher viscosity oil. 4. In summer, when engine temperatures are high, higher viscosity oil is needed to ensure the oil does not become too thin; in winter, lower viscosity oil is required to maintain proper oil flow.
As an average car owner, I once impulsively switched to a 10W-40 high-viscosity oil, only to find my car starting as slow as a snail crawling in cold weather, with fuel consumption skyrocketing. Later, checking the vehicle manual revealed my new car actually required 5W-30, teaching me that viscosity isn't about absolute good or bad: high-viscosity oils like 10W-40 offer stronger protection for engine bearings in summer or under heavy loads, preventing overheating wear; while low-viscosity oils such as 0W-20 start up lightning-fast in winter, saving fuel and being eco-friendly. But it depends on the car's age—older engines with larger gaps may leak thinner oil; newer precision engines benefit from thinner oil to reduce friction. Weather matters too—northern winters call for oils with lower first numbers. Bottom line: don't guess, the manual is gospel. Even if you're lazy, change oil seasonally to ensure engine longevity. Using the wrong viscosity usually makes the engine louder—that's your warning sign.
