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Ooops - Put in 10 Gallons of 89 Octane

12K views 20 replies 16 participants last post by  SoCalChallengerLover  
#1 ·
Has anyone else done this? I was headed home from work the other day and was not thinking when I stopped to fuel up. I absently-minded put 10 Gallons of 89 Octane in my girl and nearly cried when I realized it. /cry

I run Shell 93 exclusively and as often as I can from the same service station. There was another car in my "usual" pump and I took the next bay over... I grabbed the yellow handle to the far right, which is 93 on my usual pump, and noticed when hanging the pump up it as 89 Octane!!! Ughhh!!!

The car had a little less than a 1/4 tank when I stopped to get gass, so at least it was not empty and the mix should have been a little better than 89.. but wow, what a screw-up.

As for performance I did not notice anything for a while but as I drove this past week I could clearly feel the computer/sensor had dialed back the timing... it felt off, not poky mind you... but off. Even the exhaust sounded off to me.

Anyway, I've burned just about all of it out this week and will fill up tomorrow... making damn sure it's 93 Octane! :grin2:
 
#2 ·
Has anyone else done this? I was headed home from work the other day and was not thinking when I stopped to fuel up. I absently-minded put 10 Gallons of 89 Octane in my girl and nearly cried when I realized it. /cry

I run Shell 93 exclusively and as often as I can from the same service station. There was another car in my "usual" pump and I took the next bay over... I grabbed the yellow handle to the far right, which is 93 on my usual pump, and noticed when hanging the pump up it as 89 Octane!!! Ughhh!!!

The car had a little less than a 1/4 tank when I stopped to get gass, so at least it was not empty and the mix should have been a little better than 89.. but wow, what a screw-up.

As for performance I did not notice anything for a while but as I drove this past week I could clearly feel the computer/sensor had dialed back the timing... it felt off, not poky mind you... but off. Even the exhaust sounded off to me.

Anyway, I've burned just about all of it out this week and will fill up tomorrow... making damn sure it's 93 Octane! :grin2:
You will be ok just don't get on it. I did almost the same thing but only put 3 or 4 gallons in before I realized what I did.
 
#5 ·
I drive an sxt, so what the hell do I know. But what seems like forever ago I had a well modded firebird. If I did not put 93 in it, the engine ran rough, made knocking noises and would stall if let idle. I'm sure one of the true gear heads around here could explain the why better than that, but thats my exp


2015 SXT Plus, STP, SGII, Granite
 
#8 ·
Unlike engines of a decade or more ago (like the Firebird I assume), modern engines have knock sensors which "hear" cylinder knock and immediately dial back the timing. This stops the knock but also reduces performance. I doubt the 89 does any damage -fortunately it wasn't 87. Run the tank close to dry and fill up with 93, then forget about it.




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#10 ·
Unlike engines of a decade or more ago (like the Firebird I assume), modern engines have knock sensors which "hear" cylinder knock and immediately dial back the timing. This stops the knock but also reduces performance. I doubt the 89 does any damage -fortunately it wasn't 87. Run the tank close to dry and fill up with 93, then forget about it.




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#12 ·
I'd grab some quality octane booster from the local parts store and dump it in the tank, add some gas on top to mix it up and forget about it.

But, you don't really even need to do that. It's not going to run as well, but it's not going to grenade.
 
#15 ·
I guarantee you that when the dealer fills the car up, regardless of what the car requires, they use 87 octane. I drove mine to the station myself and filled it with 93 on the dealers credit card.

Lol yeah. I picked up my car two weeks ago. got to listening to the car idle in the driveway and man that sounds like a knock. I was thinking no way brand new car. Got to thinking well maybe the dealer but 87 in it. ran the tank down and just filled it up with 91 about a 5 days ago, half way through that tank now, and the knock is already going away, so they did put 87 in it.

I wouldnt worry about 87 or even 89 in the car, its just going to hurt performance, and if you ran it long term as in week after week, theyre might be a problem.
 
#17 ·
Stopped at a gas station that had race fuel so I did the opposite and dropped in 12gl of 100 octane liquid gold! Lol that was a great tank of gas, but it cost me $96 after I topped the rest off with 93. It defiantly made a difference in the response of my 2012 RTC. $6.99 a gal is a little cost prohibitive, but I had to try it once!