# In reverse-from premium gas to regular **URL:** \ **Category:** Maintenance/Repairs\ **Created:** [June 23, 2008, 9:03pm UTC](https://community.cartalk.com/t/in-reverse-from-premium-gas-to-regular/15746 "2008-06-23T21:03:21Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![4srco2](https://avatars.discourse-cdn.com/v4/letter/4/b77776/32.png) [@4srco2](https://community.cartalk.com/u/4srco2)\ **Post date:** [June 23, 2008, 9:03pm UTC](https://community.cartalk.com/t/in-reverse-from-premium-gas-to-regular/15746/1 "2008-06-23T21:03:21Z")
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. ---
**Author:** ![budd2049](https://avatars.discourse-cdn.com/v4/letter/b/77aa72/32.png) [@budd2049](https://community.cartalk.com/u/budd2049)\ **Post date:** [June 23, 2008, 9:09pm UTC](https://community.cartalk.com/t/in-reverse-from-premium-gas-to-regular/15746/2 "2008-06-23T21:09:43Z")
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. ---
**Author:** ![SteveF](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/stevef/32/2_2.png) [@SteveF](https://community.cartalk.com/u/SteveF)\ **Post date:** [June 23, 2008, 9:10pm UTC](https://community.cartalk.com/t/in-reverse-from-premium-gas-to-regular/15746/3 "2008-06-23T21:10:28Z")
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! ---
**Author:** ![Triedaq](https://avatars.discourse-cdn.com/v4/letter/t/65b543/32.png) [@Triedaq](https://community.cartalk.com/u/Triedaq)\ **Post date:** [June 23, 2008, 9:17pm UTC](https://community.cartalk.com/t/in-reverse-from-premium-gas-to-regular/15746/4 "2008-06-23T21:17:36Z")
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. ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [June 23, 2008, 9:19pm UTC](https://community.cartalk.com/t/in-reverse-from-premium-gas-to-regular/15746/5 "2008-06-23T21:19:46Z")
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. ---
**Author:** ![americar](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/americar/32/42_2.png) [@americar](https://community.cartalk.com/u/americar)\ **Post date:** [June 23, 2008, 9:31pm UTC](https://community.cartalk.com/t/in-reverse-from-premium-gas-to-regular/15746/6 "2008-06-23T21:31:43Z")
“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 ---
**Author:** ![the\_same\_mountainbike](https://avatars.discourse-cdn.com/v4/letter/t/c89c15/32.png) [@the\_same\_mountainbike](https://community.cartalk.com/u/the_same_mountainbike)\ **Post date:** [June 23, 2008, 9:37pm UTC](https://community.cartalk.com/t/in-reverse-from-premium-gas-to-regular/15746/7 "2008-06-23T21:37:52Z")
Yes…one poster even started a thread on that issue… ---
**Author:** ![SteveF](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/stevef/32/2_2.png) [@SteveF](https://community.cartalk.com/u/SteveF)\ **Post date:** [June 23, 2008, 10:44pm UTC](https://community.cartalk.com/t/in-reverse-from-premium-gas-to-regular/15746/8 "2008-06-23T22:44:59Z")
Yes, I remember that head case. The inmate wanted to run the asylum…