does gas lose its octane after storage?
 

Hey guys,
my car had been in storage for the past month or so and I just brought it back out this weekend. My car had been tuned to run on 94 octane gas. When I first brought it out, the car seemed a lot slower than before. Could it be because of the old gas in the car? I am currently running hondata, adjustable fuel pressure regulator...could anything have gone wrong with them during my storage?

another question is whether different temperatures would cause changes to a car's air fuel ratio? for example, if the air is colder outside, there would be more oxygen in your combustion chamber and therefore require more fuel to combust. If you keep the same amount of fuel, then the car would run lean. Is there anything wrong with my reasoning?

TIA https://honda-tech.com/forums/images...es/emsmile.gif

Re: does gas lose its octane after storage? (Type-Rare#1248)
 

Yes gas does start to lose it's octane rating after about 2 weeks. When storing a car it's a good idea to go to any auto store and purchace a bottle of Sta-bil. It is a fuel stabilizer and will help keep the gas "fresh" for I believe the bottle says 12 months

Re: does gas lose its octane after storage? (Type-Rare#1248)
 

go with the sta-bil as suggested. https://honda-tech.com/forums/images/smilies/emthup.gif

Re: does gas lose its octane after storage? (1999all_motoR_teg)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 1999all_motoR_teg &raquo;</TD></TR><TR><TD CLASS="quote">Yes gas does start to lose it's octane rating after about 2 weeks. When storing a car it's a good idea to go to any auto store and purchace a bottle of Sta-bil. It is a fuel stabilizer and will help keep the gas "fresh" for I believe the bottle says 12 months</TD></TR></TABLE>

2 weeks? really? how much of its rating does it loose within 2 weeks?

LOL

Opie, sits back and waits for formula https://honda-tech.com/forums/images...s/emsmilep.gif

No way its 2 weeks, i would say more like 2 months.

Re: (LsVtec92Hatch)
 

Gasoline life varies on where it's stored, how much is stored, and weather conditions...Gasoline can last around 3-6 months..depending on those variables...so if you plan to store you car, just run your car down to a 1/4 tank...do a double dose of STABIL Fuel Stablizer and you won't have to worry about stale or gummy gas... https://honda-tech.com/forums/images/smilies/emthup.gif https://honda-tech.com/forums/images/smilies/emthup.gif double dose will allow the gas to stay fresh for 2 years.. https://honda-tech.com/forums/images/smilies/emthup.gif https://honda-tech.com/forums/images/smilies/emthup.gif

Since you car seems sluggish, just go fill it up and run it down to 1/2 tank and refill it again...it should dillute the old gas...hope that helps...

Re: (opie)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by opie &raquo;</TD></TR><TR><TD CLASS="quote">LOL

Opie, sits back and waits for formula https://honda-tech.com/forums/images...s/emsmilep.gif</TD></TR></TABLE>


Well the formula is X molecules and Z temperature...LOL J/K https://honda-tech.com/forums/images...s/emsmilep.gif

I've heard that it starts to loose it's rating after 2 weeks, guess I was wrong LOL

Re: does gas lose its octane after storage? (Type-Rare#1248)
 

thx for the reply guys

is there anyone who could answer the second part of my question? https://honda-tech.com/forums/images...es/emsmile.gif

...octane is lost when light hits it for a large amount of time.

you will loose more octane storing your gas in a container than while in your gas tank.


as far as air fuel ratio goes...colder fuel = denser fuel so yes, you will run a tad more richer when colder, but colder fuel with colder air will almost equate out to equal the same air fuel ratio. stock computers have this compesation mapped out into its computer, so you should have around the same air fuel regardless of temp. maybe a difference of 0.1 or 0.2 air fuel when its colder outside or you have colder fuel.

Re: (visi0n)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by visi0n &raquo;</TD></TR><TR><TD CLASS="quote">
as far as air fuel ratio goes...colder fuel = denser fuel so yes, you will run a tad more richer when colder, but colder fuel with colder air will almost equate out to equal the same air fuel ratio. stock computers have this compesation mapped out into its computer, so you should have around the same air fuel regardless of temp. maybe a difference of 0.1 or 0.2 air fuel when its colder outside or you have colder fuel.</TD></TR></TABLE>

its the other way around. where do you get your information? a/f will be more lean during winter time, i had mine tuned during winter so its safe all year long. change isn't dramatic so its drivable all year long. while rsx has this feature (using several maps based on temps), ours adjust for idle/startup, closed loop will will always adjust to 14.7 but wot will lean out during colder temps. for n/a application there isn't much to worry about unless you have higher flowing exhaust setup (header/cat/catback) and intake allowing more air and leaning out. mine dynoed in 14's a/f w/ stock ecu during winter (thats with i/h/e).

Re: (vtec.dc2)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by visi0n &raquo;</TD></TR><TR><TD CLASS="quote">as far as air fuel ratio goes...colder fuel = denser fuel so yes, you will run a tad more richer when colder, but colder fuel with colder air will almost equate out to equal the same air fuel ratio. </TD></TR></TABLE>
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtec.dc2 &raquo;</TD></TR><TR><TD CLASS="quote">its the other way around. where do you get your information? a/f will be more lean during winter time, i had mine tuned during winter so its safe all year long. change isn't dramatic so its drivable all year long. while rsx has this feature (using several maps based on temps), ours adjust for idle/startup, closed loop will will always adjust to 14.7 but wot will lean out during colder temps. for n/a application there isn't much to worry about unless you have higher flowing exhaust setup (header/cat/catback) and intake allowing more air and leaning out. mine dynoed in 14's a/f w/ stock ecu during winter (thats with i/h/e).</TD></TR></TABLE>

pwned by empirical gas laws.. PV=nRT for an ideal gas.
Charles' Law:
V/T = k .. so absolute temperature decrease means volume decreases (proportionally)

The difference between a hot (30 C) day and a cold (0 C) day is a 10% reduction in volume for the air, the density is higher by about 10% too. The gas will contract a LOT less than that (when's the last time you saw a 5 gallon container of gas shrink to 4.5 gallons in the winter? Me neither, but I've seen it happen to empty containers.

Re: (vtec.dc2)
 

Wow, a lot of ppl w/ a lot of damn OPINIONS and a ton of misinformation.

Re: (Chris F)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Chris F &raquo;</TD></TR><TR><TD CLASS="quote">
The difference between a hot (30 C) day and a cold (0 C) day is a 10% reduction in volume for the air, the density is higher by about 10% too. </TD></TR></TABLE>

i said nothing about gas. air is more dense during winter and will raise a/f ratio a bit.

Re: (vtec.dc2)
 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by vtec.dc2 &raquo;</TD></TR><TR><TD CLASS="quote">i said nothing about gas. air is more dense during winter and will raise a/f ratio a bit.</TD></TR></TABLE>

I was trying to agree with you!! I just added that bit about the gas because it "does" contract just a little bit. https://honda-tech.com/forums/images...es/emsmile.gif

Re: does gas lose its octane after storage? (Type-Rare#1248)
 

If you're worried about octane, you can toss a gallon or two of Toluene/Xylene in your gas tank (about 118 octane) from a paint store. You can find it for $5-$6 a gallon if you look.
That is, if you're too impatient to burn off your current tank https://honda-tech.com/forums/images...es/emsmile.gif
https://honda-tech.com/zerothread?id=1032265
-Chris