1. Increased resistance to flow: High viscosity oil has a thicker consistency and flows more slowly than low viscosity oil. As a result, it creates more resistance to flow within the engine's oil passages and galleries. This restriction can lead to decreased oil flow to critical engine components, such as the pistons and bearings, which can cause them to overheat.
2. Reduced heat transfer: High viscosity oil also reduces the oil's ability to transfer heat away from hot engine components. As the oil circulates through the engine, it absorbs heat from the engine parts and carries it away to the oil cooler. However, high viscosity oil has a lower thermal conductivity than low viscosity oil, so it is less effective at transferring heat. This can cause the engine to run hotter overall.
3. Increased oil pumping work: The engine's oil pump has to work harder to circulate high viscosity oil than low viscosity oil. This increased pumping work can generate heat, which can further contribute to engine overheating.
4. Clogged oil passages: High viscosity oil is more likely to form deposits and sludge in the engine's oil passages and galleries. These deposits can restrict oil flow even further, leading to increased engine temperatures.
In summary, high oil viscosity can cause engine overheating by reducing oil flow, reducing heat transfer, increasing oil pumping work, and clogging oil passages. It is important to use the correct oil viscosity for your engine as specified by the manufacturer to avoid overheating and other engine problems.
