Technician A says that 10% Ethanol (E10) is acceptable for modern small engines. Technician B states that 15% Ethanol (E10) is acceptable. Who is correct?

In the context of modern small engines, 10% ethanol (E10) is commonly accepted as a safe and effective fuel option. Most contemporary small engines are designed to handle this blend without experiencing significant problems. Ethanol can contribute to issues such as fuel system corrosion and poor performance if present in higher concentrations, particularly in older engines or those not designed for ethanol blends.

Technician A correctly identifies that E10 is acceptable for modern small engines, which is widely supported by manufacturers and the industry. This blend offers a level of ethanol that can help improve combustion efficiency while minimizing the associated risks linked to higher ethanol concentrations.

On the other hand, Technician B's claim regarding the acceptability of 15% ethanol (E15) in modern small engines is generally viewed with caution. While some newer vehicles and engines may be rated to handle E15, many small engine manufacturers advise against it due to potential complications such as fuel degradation, compatibility issues with fuel system components, and risks of engine damage over time.

Therefore, the assertion that E10 is suitable for use in modern small engines validates Technician A's statement as correct in this scenario.