Is Higher Oil Viscosity Always Better?
1 Answers
Higher oil viscosity is not always better. Here are the impacts of oil viscosity: 1. Difficulty in cold engine starts. If the oil viscosity is too high, oil circulation during cold starts will be slow. Although oil pressure may be high, the actual oil flow rate is low due to poor pumpability caused by high viscosity. This often leads to temporary dry friction or semi-fluid friction, which is a major cause of engine wear. 2. Poor cooling performance. Higher viscosity oil has poorer fluidity and slower circulation speed, resulting in slower heat dissipation from friction surfaces and consequently inferior cooling effects, which may cause engine overheating. 3. Inferior cleaning capability. High viscosity oil circulates more slowly and passes through filters less frequently, making it harder to remove metal particles, carbon deposits, dust and other contaminants from friction surfaces, thus reducing cleaning effectiveness. 4. Conversely, oil with too low viscosity may not form a sufficiently thick oil film on high-temperature friction surfaces. The load-bearing capacity of such thin oil films is poor and they can be easily broken under pressure, failing to provide proper lubrication and potentially increasing wear.