In general, the octane needs of a vehicle align with the manufacturer’s recommendation. However, a small percentage of vehicles may require higher octane fuel under certain conditions. Extremely hot weather, changes in altitude, or exceptionally hard driving conditions, such as towing heavy loads, may cause knocking. Additionally, knocking may be the result of slight variations in engine construction variability or unusual engine deposit build-up. Many modern vehicles are equipped with electronic knock sensors that detect and eliminate light knocking before you hear it.