What are the effects of excessively high engine oil viscosity?

[Chris]

Here are the effects of excessively high engine oil viscosity: 1. Difficulty in cold engine starting. During cold starts, the oil flows too slowly, resulting in high oil pressure but insufficient oil circulation. The poor pumpability of the oil increases wear on engine components during the period from startup until oil reaches the friction surfaces. 2. Significant power loss. High oil viscosity increases friction resistance on component surfaces, leading to greater wear and higher frictional power loss. Additionally, the crankshaft's oil churning resistance increases, causing more internal power loss and reducing the engine's effective power output. 3. Lower RPM and difficulty in ignition. Excessive oil viscosity requires higher torque for crankshaft rotation during cold starts, resulting in lower RPM and ignition difficulties. 4. Poor cleaning performance. High viscosity oil circulates slowly, reducing the frequency of passing through the filter. This makes it harder to remove metal particles, carbon deposits, and dust from friction surfaces, impairing cleaning effectiveness. 5. Inadequate cooling. Thick oil flows poorly and circulates slowly, reducing the rate at which heat is carried away from friction surfaces. This results in poor cooling performance and increases the risk of engine overheating. 6. Higher carbon residue. High viscosity oil produces larger carbon residue particles with higher solidification points, which can easily clog oil passages.