# Fuel octane mixing/combining **URL:** \ **Category:** Power/Fuel\ **Tags:** gasoline\ **Created:** [August 26, 2008, 2:35am UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672 "2008-08-26T02:35:58Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![Askren](https://avatars.discourse-cdn.com/v4/letter/a/dc4da7/32.png) [@Askren](https://community.cartalk.com/u/Askren)\ **Post date:** [August 26, 2008, 2:35am UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/1 "2008-08-26T02:35:58Z")
If you use a mixture of half 89 octane and half 93 octane, does it mix and become a whole tank of 91 octane or do I just get 89 or 93 depending on what is injected at that exact instant? My car calls for a minimum of 91. All that is sold around here is 89 and 93. If you just get 89 or 93, can and does the computer detect quickly enough to retard or not for each stroke? I have tried a mix and can’t feel any difference in performance. Can the mix damage the engine if it does not convert to 91 and does not retard quickly enough? ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [August 26, 2008, 2:43am UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/2 "2008-08-26T02:43:12Z")
Mixing works fine, that’s how pumps dispense 91, by mixing 89 and 93. ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [August 26, 2008, 3:10am UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/3 "2008-08-26T03:10:06Z")
The pumps don’t mix it, the tanker driver does when he delivers the load. “Mid Grade” is a 50-50 mix, regular and premium, dumped in a third tank. At least you HOPE that’s what it is… ---
**Author:** ![texases](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/texases/32/862_2.png) [@texases](https://community.cartalk.com/u/texases)\ **Post date:** [August 26, 2008, 3:18am UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/4 "2008-08-26T03:18:16Z")
It depends on the gas station - remember the Sunoco pumps, with what, 5 grades? Those were mixed, and I’ve read some do the same for mid-grade. ---
**Author:** ![lion9car](https://avatars.discourse-cdn.com/v4/letter/l/59ef9b/32.png) [@lion9car](https://community.cartalk.com/u/lion9car)\ **Post date:** [August 26, 2008, 3:31am UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/5 "2008-08-26T03:31:15Z")
It mixes and becomes 91. I have always wondered if it mixes well just from pumping the gas or if it needs to slosh around for a bit before it’s fully mixed. ---
**Author:** ![Tester](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/tester/32/15976_2.png) [@Tester](https://community.cartalk.com/u/Tester)\ **Post date:** [August 26, 2008, 4:18am UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/6 "2008-08-26T04:18:35Z")
Let’s see? These chemical engineers figured out what additives to add to the gas so the octane level remained a constant? And all of a sudden you want to try to out-engineer all that effort to do what? I just don’t get it? Tester ---
**Author:** ![lion9car](https://avatars.discourse-cdn.com/v4/letter/l/59ef9b/32.png) [@lion9car](https://community.cartalk.com/u/lion9car)\ **Post date:** [August 26, 2008, 10:35am UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/7 "2008-08-26T10:35:53Z")
The OP doesn’t want to pay for 93 when his or her car requires 91. It sounds like a perfectly reasonable question to me. (How many times do we tell people here not to pay for a higher octane than what the car requires?) ---
**Author:** ![andrew\_j](https://avatars.discourse-cdn.com/v4/letter/a/91b2a8/32.png) [@andrew\_j](https://community.cartalk.com/u/andrew_j)\ **Post date:** [August 26, 2008, 11:05am UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/8 "2008-08-26T11:05:41Z")
My local station has 5 octanes available. Do you really think they have fix tanks in the ground? ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [August 26, 2008, 2:34pm UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/9 "2008-08-26T14:34:45Z")
Most stations in my area only have 2 tanks (regular and high-test). The mid grade is mixed from the two. Far cheaper for a station to have 2 tanks then 3 or 5 (like Sunoco and their 5 grades). ---
**Author:** ![MikeInNH](https://avatars.discourse-cdn.com/v4/letter/m/a587f6/32.png) [@MikeInNH](https://community.cartalk.com/u/MikeInNH)\ **Post date:** [August 26, 2008, 2:36pm UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/10 "2008-08-26T14:36:20Z")
Exactly. My 4runner requires 91. No one sells 91 Octane. It’s either 87, 89 or 93. So I mainly use 93 and mix in 89 when I’m down to half a tank. Then the next fillup I put in 93. ---
**Author:** ![FoDaddy](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/fodaddy/32/717_2.png) [@FoDaddy](https://community.cartalk.com/u/FoDaddy)\ **Post date:** [August 26, 2008, 3:21pm UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/11 "2008-08-26T15:21:31Z")
Sounds like a lot of trouble to go through to save maybe $2. ---
**Author:** ![Caddyman](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/caddyman/32/23_2.png) [@Caddyman](https://community.cartalk.com/u/Caddyman)\ **Post date:** [August 26, 2008, 7:00pm UTC](https://community.cartalk.com/t/fuel-octane-mixing-combining/18672/12 "2008-08-26T19:00:52Z")
everyone else’s 4-runner runs fine on 87…