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Does gasoline lose octane over time? (Tune related)

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Old 05-19-2013, 12:47 PM
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Esch
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Default Does gasoline lose octane over time? (Tune related)

My car is a nice-weather weekend car that does not see all that many miles, especially over the Winter months. Over the Winter I can go for as long as 6 months between fill ups, but I do add stabilizer when I fill up for the last time before it sits for a while.

My concern is, when I load a higher octane tune (93), will I run into issues if I'm not filling up at least once a month or so? Currently I have a nearly empty tank with 87 in it (with a Bama 87S tune), but I plan on running through a tank of 93 before loading a 93 tune. I then don't want to run into problems if the octane rating lowers over time while I have a 93 tune loaded... or is this not something to worry about? I suppose I could continue filling up with 93 and then run a 91 tune to be safe, but I'd prefer to run a 93 tune with 93 gas if possible.

Any thoughts?
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Old 05-19-2013, 05:35 PM
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you need to add stabilizer before the fuel sits...adding it afterword wont help old fuel. The main problem with letting fuel sit is some of the components of the fresh fuel evaporate, lowering the volatility and the fuel can become contaminated with water from the air. I cant comment on what could happen with a car engine if you run it. I read that higher octane fuel can degrade in only 60 days...there is also no good way to know how old the fuel was when you first bought it...if its not too much, maybe you can siphon it out and use it for the lawnmower.

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Old 05-19-2013, 06:20 PM
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My Stang will often sit for a few months with the same fuel and I haven't noticed a problem with my 89 tune. When I used to store the Stang over the winter (when I lived in that god-forsaken north) I used stabilizer. But now I use ethanol free fuel plus I'll occasionally use stabilizer when I know it'll be awhile before she gets her tank emptied.
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Old 05-20-2013, 06:30 PM
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Originally Posted by vixr View Post
you need to add stabilizer before the fuel sits...adding it afterword wont help old fuel. The main problem with letting fuel sit is some of the components of the fresh fuel evaporate, lowering the volatility and the fuel can become contaminated with water from the air. I cant comment on what could happen with a car engine if you run it. I read that higher octane fuel can degrade in only 60 days...there is also no good way to know how old the fuel was when you first bought it...if its not too much, maybe you can siphon it out and use it for the lawnmower.
I do add the stabilizer as soon as I get home from filling up towards the end of the year.
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Old 05-20-2013, 06:49 PM
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Originally Posted by Esch View Post
I do add the stabilizer as soon as I get home from filling up...
Incorrect method. You're not getting the proper mixing required to provide protection, nor is any of the properly treated fuel getting thru your fuel system. Add the stabilizer at the pump BEFORE filling to allow the stabilizer to mix from the force of the fuel entering the tank. Then, as you drive home (as long as it's more than just a couple of miles), the treated fuel is now in the lines, injectors, etc at time of storage.
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Old 05-21-2013, 07:22 PM
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Originally Posted by Nuke View Post
Incorrect method. You're not getting the proper mixing required to provide protection, nor is any of the properly treated fuel getting thru your fuel system. Add the stabilizer at the pump BEFORE filling to allow the stabilizer to mix from the force of the fuel entering the tank. Then, as you drive home (as long as it's more than just a couple of miles), the treated fuel is now in the lines, injectors, etc at time of storage.
I should have clarified that I do drive it (more than just a few miles) after adding the stabilizer. I don't have a set date that I put the car away or anything. When I know I'll be filling up for the last time before Spring, I fill up, drive home, add the stabilizer, then go for a drive. There will often be at least a few more times I take it out before the first snow hits and I throw the battery tender on it.
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Old 05-21-2013, 11:43 PM
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Originally Posted by Nuke View Post
Incorrect method. You're not getting the proper mixing required to provide protection, nor is any of the properly treated fuel getting thru your fuel system. Add the stabilizer at the pump BEFORE filling to allow the stabilizer to mix from the force of the fuel entering the tank. Then, as you drive home (as long as it's more than just a couple of miles), the treated fuel is now in the lines, injectors, etc at time of storage.
You guys are being wimpy. No need to store your stang. Blizzaks. Saves money on fuel stabilizer
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Old 05-22-2013, 09:26 PM
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Gasoline does not lose octane over time. It degrades.

That said, every single tier one gasoline supplier in the United States has a minimum one year storage life for gasoline.

Adding Stabil for winter storage is a complete waste of money unless your winters are 13 months long. Using one tank of gasoline per month doesn't require anything but filling up once a month.

The Chevy Volt has a battery pack that's charged overnight and a gasoline engine that acts as a generator if you drive further than the small battery's range (about 40 miles). If you drive less than 40 miles a day and recharge every night, the gasoline engine will never turn on. Drive over 40 miles, the engine kicks in and generates electricity for the electric motor powering the drive wheels.

Chevrolet has programmed the Volt's computer to deal with the possibilty of stale gas. If you drive only on the electric charge, the gas engine will never turn on and you eventually wind up with nine gallons of goo.

Several Volt owners have reported driving over a year without using any gasoline and the Volt's computer turns on the gas engine around thirteen months (there are variables) after the last fill up to burn the gasoline before it goes stale.

No additives required with brand name fuels. Yes, I've personally spoken with specialists at Conoco-Phillips and Chevron and have a Conoco-Phillips White Paper to verfy this

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Old 05-22-2013, 09:33 PM
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Originally Posted by wcgman View Post
You guys are being wimpy. No need to store your stang. Blizzaks. Saves money on fuel stabilizer
I had Blizzaks on my Subaru Legacy GT. Got through some winter this year with Hankook all season high performance tires on my '04 Mach 1 with no problems.

Once I realized I can drive a Powerstroke 4X4 in winter mostly in 2wD with 570lb.ft. torque and an empty bed without hitting anything, the Mustang was a piece of cake on all season tires. Just be gentle with the throttle and don't drive faster than conditions allow. Most people drive way too fast in winter regardless of tires.
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Old 05-22-2013, 11:45 PM
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Good question I was actually thinking the same thing since after this weekend hopefully I will be getting a daily driver and mine will no longer be driven daily. I wonder this because my car is supercharged and is tuned for 93 octane.
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