Understanding the Difference Between 93 Octane and 95 Octane Petrol
If you are in the UK, you might find it challenging to find 93 octane number fuel. The lowest octane fuel available at the pump is usually 95 octane RON. However, it’s important to note that in North America, they refer to the Anti-Knock Index (AKI) as the octane rating, which can sometimes lead to confusion. The Research Octane Number (RON) is the more accurate term used to describe the octane rating as it refers to the comparison with 100 iso-octane fuel, which has an octane number of 100.
The AKI and RON Relationship
The Anti-Knock Index (AKI) is actually the average of two tests: the Research Octane Number (RON) and the Motor Octane Number (MON). This average gives us the PUMP OCTANE number, which is a more accurate description of the fuel you are getting at the pump. Typically, mid-grade fuel with an AKI of 93 is around 98 RON, and mid-grade with an AKI of 95 is nearly 100 octane RON.
In the US, 93 AKI is approximately 98 RON, and 95 AKI is close to 100 RON. However, finding 95 AKI outside of a race track, especially in California, can be quite difficult. If you do have the opportunity to mix these fuels in a 50/50 ratio, you will end up with 94 octane, which is very close to the standard mid-grade fuel in both the UK and the US.
Blending Fuel: The Reality at the Pump
Most stations have two fuel tanks, one with 93 octane and another with 95 octane. The blending dispenser at the pump mixes fuel from both tanks to give you the desired octane level. The pumps are in the tanks, and the customer only interacts with the dispenser to fill their car. Therefore, the actual octane of the fuel you get is dictated by the blend of these two grades.
For example, if you have one cup of 93 octane and 18 gallons of 94 octane, the overall octane would not remain at 94. Instead, the blend would be closer to the higher octane level. However, if you mix these fuels in a 50/50 ratio, you will end up with 94 octane. But if you mix other percentages, you need to use simple math to figure out the resulting octane rating.
Practical Considerations for Mixing Octane Levels
It is important to note that modern vehicles are designed to handle the small variations in octane levels. If you mix 93 and 95 octane fuels in equal parts, you will get 94 octane, which is a reasonable compromise for fuel economy and performance. The difference in octane rating between 93 and 95 is relatively minor, and most drivers would not notice a significant difference in their vehicle's performance.
However, for older or specialized vehicles, you should be more cautious and refer to the manufacturer’s guidelines to ensure that the octane level is suitable for your engine. In such cases, sticking to the recommended octane rating is the safest and most reliable option.
Combining different fuels can be a cost-effective solution if you determine that the blend is sufficient for your needs. Always ensure that you understand the octane levels of the fuel you are using and adjust accordingly to maintain optimal performance and fuel economy.