Technician A says all vehicles use the same oil viscosity. Technician B says using the wrong viscosity oil can damage an engine. Who is correct?

Using the wrong viscosity oil can indeed damage an engine, which is why Technician B's statement is accurate. Engine oil viscosity is essential because it determines how easily the oil flows and lubricates engine components. Each vehicle has a specific oil viscosity recommended by the manufacturer based on the engine's design, temperature range, and operating conditions. If an oil with the wrong viscosity is used—either too thin or too thick—it can lead to inadequate lubrication, increased wear and tear, overheating, or even engine failure.

In contrast, the assertion made by Technician A that all vehicles use the same oil viscosity is not accurate, as different engines require different viscosities based on their unique specifications and operating requirements. This distinction is crucial for maintaining engine health and performance, thereby highlighting why Technician B's comment about the risks of using incorrect viscosity oil is correct.