Why is the Ron value so low on fuel in the US?

12 comments

1. It’s not the same rating scale. The fuel is very similar though when adjusted. Your 95 is roughly our 91

2. Because our value are displayed in AKI instead of RON.

3. Ron Burgundy?

4. This might help… https://bobistheoilguy.com/forums/threads/octane-conversion-chart-us-vs-eu.373446/

5. Because it is not the RON in the US. It’s the AKI, which is an average of the RON and the MON.

6. AKI=(RON+MON)/2

7. US premium wouldn’t be 91 RON, it’d be 91 AKI (anti-knock index), which is the average of RON and another number called MON. That 91 AKI would be roughly equivalent to 95 RON, but US premium is also often 93 AKI, which is more like 98 RON. The minimum [varies by state](https://en.wikipedia.org/wiki/List_of_U.S._states_by_standard_octane_ratings), with higher-altitude states tending to have lower minimums because a car will run the same with a lower octane rating at higher altitudes.

   The number that’s actually lower in the US is the cetane number of diesel fuel. Some of the *very* few people that drive diesel passenger vehicles in the US use cetane boosting additives at each fill-up (although that’s by no means necessary).

8. Another thing to note: In the west, many Americans live at much higher elevations than the average European, so we can safely drive with lower octane ratings without engine knocking.

9. okay, I googled and was not immediately made aware what the hec ron value is.

   I would assume California regs influence our national auto emissions.

10. [deleted]

11. Because the US use the Anti-Knock index and we use the Research Octane Number.

    Lots of comparisons online betwen AKI, MON and RON

12. The RON value is no different. But we don’t sell gasoline by RON value. It even says so on the pump and in the car manuals.