After 48 years of driving I thought that I knew how to fuel a vehicle. That changed when we began traveling through Idaho and Wyoming. Take another look at that gas pump photo. Did you see something odd? No, it is not only the high cost of gasoline: It’s the Octane rating! Regular unleaded gas in Idaho and Wyoming had an Octane rating of 85. “Unleaded Plus” gas was 87 Octane.

I had never encountered 85 Octane fuel before. I was tempted by the price but thought to check the owner’s manual of our Ford Transit chassis to ensure the engine would run on 85. It indicated that the engine required a minimum of 87. As it turns out most automobiles require a minimum of 87 Octane and some require a minimum of 89 or higher.

So why is 85 Octane gas sold? It’s fine for carburetor-fueled engines that are used at a high altitude. Unfortunately, cars stopped using carburetors in the 1980’s. Use of 85 Octane (or Octane ratings lower that the minimum required by your car or truck) can potentially damage the engine.

I am writing this as we are traveling through Oregon and the 85 Octane gas is gone. Gas advertised as “Regular” has returned to 87 Octane. So now I can confidently press the left-most gas button and fuel our rig without worry. All I need to watch out for is E85 “gas”.