Can you mix old gas with new to blend to reuse?.

 

Define what old is? Some on here think gas from last summer is old.

 

in your riding mower, and in your more modern efi car less so but yes. i have done both. old boat gas. but i would never think about it in a carb'ed car that gets the gas pedal pushed hard. especially first time out in a long time. you will be too tempted to open her up and roast pistons with the lowest octane gas there is.

 

I wrote an article for a magazine about how long gas lasts without expensive and useless additives. Most of the major oil companies told me that two years in a full tank is no problem. I have mixed fresh gas with stuff that was three or four years old and the car ran perfectly. (A 1975 Triumph and a 1969 Firebird).
Yes, if you let gas sit in a half empty tank for a long time, (five years or more), you may have a problem, but this whole "old gas" thing is, IMHO, overblown.
If the car runs funny, which seems unlikely, when you get down to 3/4 of a tank, fill it with fresh fuel again.
As cousin Vinny says, "Done worry about it."

 

I dont know man... i used to think so!

Then i bought this 73 coupe. It had about 1/4 tank ov gas bought roughly one year before i got there. The thing ran so bad i thought i had a bad engine. Then with some tuning i thought i just had bad plugs/wires. I didn't even bother thinking about the gas because i've never had a problem with old gas. At one point my 68 Cadillac had 5+ year old gas, in a nearly empty tank... ran great. This thing ran like it was missing two plugs. Or maybe 94 octane (Cadillac) just keeps better than 87? Was just about to dig into this engine when i just dumped about $20 ov new gas in there... POW! Brand new engine. I know gas isn't what it used to be, but man. Eye-opener.

 

Yes that is what i thought drain down as much possible and refill with new gas! Thanks guys i will let you know what happens!

 

just drive it. no full throttle. the higher ethanol amounts make the gas age less well. and you don't know if it is ethanol free, 10 or 15%

 

Hey knock it off, man! My wife still believes my excuse for taking the car on a good long rip after storage is to burn off "last year's gas".

 

I once tore my hair out trying to track down a problem that turned out to be stale gas. I think how long gas lasts in storage has everything to do with the quality of the fuel in the first place. I have used ten year old avgas (although not in an airplane) that ran perfectly, and I've burned last year's regular that ran like crap. With all that said, I mix old gas with new to use it up all the time (although not in my airplane - not willing to take a chance on falling out of the sky).

 

I run 91 octane in my hot rods. A couple sit from Oct until April. Zero problems. Also my zero turn lawn mower sits over winter with 87 octane gas and again no issues.

 

My brother is a motorcycle/snowmobile mechanic, and he winds up with a gallon or two of "Old, rotten gas" as he calls it, all the time in the springtime when people are having their toys serviced after the long winter nap. If it's only a gallon or two, you can just dump it in the tank of your daily driver (if it has a decent amount of fresh gas in it already) and it's not going to hurt anything. I do it several times every spring. That's my brother's busy season. Woo-hoo, free gas!

Scotty

 

I have mixed 50,50 old with new and it runs fine.
Not a high compression motor though.

 

I once let my 11:1 LT-1 sit six months or so with 1/4 tank of winter season gas. The winter gas is blended differently with more lighter hydrocarbons so it still makes a reasonable amount of vapor in cold weather. These lighter hydrocarbons will evaporate much too quickly in warmer weather. Especially with a vented gas tank / cap. When I started my car up in the summer, it ran so bad I thought something had broken in the motor. I could barely pull it out of the driveway. Added a five gallon can of summer blend to it, and then drove it straight to the gas station. Was fine after that. Left about 5 gallons of the old crap in there, no harm.. It was always a heavy "drinker" so it burned it up pretty quick.

 

Got The Plastic Pig together tonight. Tank filled early Dec, so close to 6 months. Dropped the distributor in, lined up all the marks, turned the key and well turned it some more to fill the float bowls, gave the pedal a couple stomps and VROOM!

 

I have read that the gasoline with ethanol (Oxygenated) in it is not going to last more than a few months in High humidity, warm conditions. I put some (~10 gallons) premium Sunoco 93 Octane in my tank and left it for 6 months and the car was not happy at all. I then added fresh gas and the problem was not as bad but the engine was stilling missing. I poured of bottle of the "Mechanics Helper" in the gas tank and put another gallon in to mix it up and the car ran "tolerably". I went to the plastic fuel tank that had the old gas in it that had been poured into the Corvette last fall and it was a much darker yellow and did not even smell like gasoline anymore. Maybe it is time to measure the specific gravity of the gas when it is fresh and then again a few months later. This could be done with the spare gas I keep in Five gallon jugs for my Ride on lawn mower. The five gallons works for the entire season so I might start watching it more closely. I drain all my gas powered tools after each season and leave the tank and carburetor bone dry.

Are all of you using gasoline treated with 10% Ethanol? I understand that in some parts of the country they still only get real pure gasoline without any ethanol. I have to go about an Hour away to have the privilege to pay more for plain gasoline. Pure gasoline will clearly last longer then the oxygenated stuff as the ethanol absorbs moisture and this dilutes the fuel and makes too much water for the car to run properly. My ride on mower has problems towards the end of season with the gasoline so I started using the Mechanic Helper and that makes it run normally even with the crap in the fuel tank. I would imagine if I had a tank full of 6 month old gas I would probably add a bottle of the Mechanics Helper to it just to be safe.

Mixing it your newer DD might be a okay use for it but from now on I am treating every gallon that I bring home in plastic fuel cans.

 

We have ethanol here in Omaha but almost every station in town also sells real gas. Cenex even has ethanol free premium.
Kind of funny since Nebraska is the second largest producer of ethanol in the country...

 

LOL, there is a message here!

 

please keep telling people that gas doesnt go bad. I love it. I get more free snowblowers and lawnmowers from folks not using Stabil than I can believe. Ethanol is not gasoline. ITs closer to Methanol. It has lousy fuel mileage, takes more energy to burn it and absorbs water. So please, keep telling all the folks how great it is and I will continue to get free stuff to clean and resell for good money. Cleaning and rebuilding carbs or replacing the old ones that arent ethanol friendly is easy so by all means, carry on. Unless of course you own tri powers, then you have better use an ethanol stabilzer or drain those carbs each winter cause I cant afford to fix your junk if its rotten.

As for mixing it in your $50,000 car, I wouldnt, I would mix it in with your fuel for your lawn mowers. Fill a five gallon jug with your old fuel and slowly mix it in with the good fuel maube 10:1. We are all old enough to remember good gas back in the day. Yes it could last 2 years and still run okay. I remember that. You would sniff it and if it didnt smell like turpentine you could use it. But today with catalytic convertors and the fuel having alcohol in it those days are gone. THe alcohol evaporates off faster and the chemical mixture of the fuel changes and whats left isnt what you bought. It will still burn but not like it did. And you have more water left behind as the alcohol leaves. Just go get a glass jar and fill it half full of fuel and sit it somewhere in the sun to evaprate for a day or 2 without letting rain get in it. watch for the color change , the odor change and the water gather in the bottom. Let it go longer and swirlk it and you will notice it will get thicker and stick to the walls of the glass given enough time for all the alcohol and a few other chemicals to eveporate. Let almost all of it go and see what the goo is that is left.

 

RR, what's the backstory on this mess ^^^^?

 

thats was a set of tripowers I bought that came off a running car that eventually I made into the Franken carbs. Ithiknk it was 2 complete sets to make one running set, mayve a feew more peices than that. The owner said he never really got into the outboard carbs, it was cruiser. If he had once in a while, meaning once everytime he drove it, the gas wouldnt have had a chance to separate and the water wouldnt have done all this corrosion. I sent another set to Holley this past winter that I got and they said the 2 outboard carbs were almost as bad as these and were unusable. I took that 2 OB carbs I had on my car and took them apart to send them in and saw a tiny bit of white crud growing in them from just sitting over the winter with no stablizer in it. I had just not gotten a chance to fill the car and had just a 3/4 tank in it from the previous season. I forget what my excuse was but I wont do that again. Unfortunately for Chevy they decided not to use the idle circuits like Mopar did on their later Six pac outboard setups or outboard accelerator pumps. We have a totally different base plate THat would have been a big help in preventing this

THose original carb bodies are made of a softer aluminum that just doesnt hold up well. Rumor is they want to up the ethanol to 15%, heard that in the very early spring but with all the other crap going on I dont know if the Gov will get to it. It needs to be eliminated fully.