In the right amount, fresh engine oil will better protect against excess friction during cold starts while offering maximum lubrication during extreme hot weather. Every gas or diesel engine can only accommodate a prescribed amount of oil, and pouring too much into the crankcase will cause the oil to foam or thicken, essentially disabling the oil’s ability to flow in hot or cold operating conditions.
If the oil can’t flow, it cannot pass through the tiny oil passages to lubricate the valvetrain, combustion chamber, pistons, and other internal components. It’s no different from vigorously churning milk and turning it into butter, and a thicker, buttery consistency is not what an engine needs to prevent it from breaking down.
Moreover, more oil means raising the oil pressure unnecessarily, which leads to leaky gaskets and oil seals. If your vehicle suddenly has an illuminated check engine light after an oil change and has symptoms like blue or white smoke, subpar performance, or unusual engine noises, it could mean the engine is drowning in oil.