Colorado Gas Pumps Offer 85, 87 and 91. What’s the Difference?
The price of gas has become a news headline lately. Currently in Colorado, the choice between 85 and 87 is what can keep your cost under $4 per gallon. But should you use 85 in your car?
In your car manual and sometimes the fuel door, you can find the suggested factory recommendation to maintain your car. But, for the sake of cost, a lot of people use a lower level than may be recommended. Colorado is one of just a few states with the 85 octane choice, while lots of other states have a choice for 93. So, what is the difference between all these octane ratings at the pump?
These ratings have to do with an air-fuel ratio and combustion. Altitude and the year of your car have to be factored in. Using the properly rated gas helps you avoid engine knocking or pings. According to Firestone engine knocking "occurs when fuel burns unevenly in your engine's cylinders."
So as far as I can tell, if you're sticking around higher elevations you could try 85, but if you're taking a road trip to lower elevations, it's probably not a good idea.
The director of Colorado’s Division of Oil and Public Safety at the Department of Labor and Employment told CPR that "air is less dense at higher elevations, reducing the chance of engine knocking when using a lower-octane gas."
"Older cars with carburetors could operate with lower octane fuel at higher elevations" according to Wikipedia, but now way less cars have carburetors.