Octane Adjustments

Note that an octane rating that suffices in the wintertime may not be adequate in the summertime. It may be necessary to go up one grade in gasoline during the summer to prevent minor knock. This is easier than having a professional automotive technician perform seasonal mechanical adjustments. Other factors, besides higher outside temperature, that tend to promote engine knock and therefore increase octane requirements are:

1. Additional vehicle weight or increased engine load, like going uphill, pulling a trailer, or using a car top carrier.
2. Lower humidity of outside air.
3. Engine runs hot due to cooling system inefficiencies.
4. Car is driven at lower altitudes (greater atmospheric pressure).
5. Engine fuel/air mixture is too lean.
6. Engine is supercharged or turbocharged.

SYSTEMS
FUEL
GASOLINE GRADE (OCTANE)
UNDERSTANDING OCTANE