Question

two technicians are discussing which oil to use for an oil change. technician a says that if a cars oil cap calls for 5w - 20 a 0w - 20 engine oil may be used. technician b says that if 5w - 30 is used in a car that is designed for 5w - 20 the check engine light may come on. who is correct?
technician a
technician b
both technicians
neither technician

Explanation:

• Technician A: 0W - 20 is a lower - viscosity oil in the winter (the "W" stands for winter) compared to 5W - 20. Lower - viscosity oils (like 0W - 20) can be used in place of higher - viscosity winter - rated oils (5W - 20) as they still meet or exceed the performance requirements for cold - start protection.
• Technician B: Using a higher - viscosity oil (5W - 30 instead of 5W - 20) can cause the engine control module (ECM) to detect differences in oil pressure or flow. Modern engines are calibrated for a specific oil viscosity. When the viscosity is higher than recommended (5W - 30 instead of 5W - 20), the ECM may set a diagnostic trouble code, and the check engine light may illuminate.

Answer:

Both technicians.