In reverse-from premium gas to regular


#1

I have a 03 F150 HarleyDavidson super charged engine. My manual states use premium 91 octane. But you cant buy 91 octane-only 93 octane. First- isnt this harmful? Second- can I use 89 octane? Id like to save some dimes per gallon.


#2

Using octane higher than what’s required isn’t harmful, but going below that may well be. Use the 93.

Most of the time using a lower octane fuel than required will impact the gas mileage to the point where what you saved at the pump is lost. It may wind up even costing you more. (I’ll assume this applies to motorcycles as well as cars)

Does it say REQUIRED, or RECOMMENDED? Given this is a supercharged engine, I bet it’s required. Don’t skimp out, give the engine what it needs to run right.


#3

If you buy a half tank of 93 octane and a half tank of 89, guess what? You have a full tank of 91 octane!


#4

This reminds me of the old Sunoco blending pumps. The stations had two underground tanks, yet had half a dozen or so different octanes that could be selected at the pump.


#5

I would not recommend going below the recommended octane on a supercharged engine. Preignition can damage an engine.

You’ve chosen performance over economy. Now you need to meet the performance engine’s demands.


#6

“If you buy a half tank of 93 octane and a half tank of 89, guess what? You have a full tank of 91 octane!”

This is what I was going to suggest, however this could create quite a disturbance in a long line at Costco


#7

Yes…one poster even started a thread on that issue…


#8

Yes, I remember that head case. The inmate wanted to run the asylum…