C2 - What Chemical chg makes for bad gas?

[Tom D.]

Had some old gas in my car and the 327-250HP engine hated that stuff. I wonder from the chemical point of view, what happens over time? How long does it take and can the process be slowed?

Also, how do I recycle or safely dispose of what I removed?

Thanks
Tom Dingman
NCRS 4889

[Joe L.]

Re: C2 - What Chemical chg makes for bad gas?

Tom------

Well, the "raw material" from which the gasoline is made, crude oil, is pretty stable for a long period of time. After all, it's MANY 1,000's of years old when it comes out of the ground. So, in burning gasoline, we're really burning "antiquity". However, the refined product is not so stable. Gasoline is not a single chemical compound. It's a MIXTURE of many, seperate and distinct chemical compounds. It's formulation changes around the country and at different times of the year.

Upon sitting for awhile in an open vessel (like a carburetor), certain of the more volatile fractions might evaporate off. This degrades the gasoline becuase it's performance is based upon its complete formulation---take away just one of the ingredients and it may be drastically changed. Also, all of the components of gasoline being ORGANIC compounds, these naturally degrade with time. If they didn't, there would be any "expiration date" on medications.

I've never had any problem with old gasoline. I once used a 5 gallon can of gasoline that had been stored for about 10 years and it worked just fine. The general appearance of it, which I inspected before adding it to the tank, looked perfect----no sludge or varnish of any kind. However, this had been stored in a SEALED container. In an open container, that might not be the case. In a sealed container, there is minimal loss of volatile components.

The gasoline has to be disposed of as a hazardous material. It so-qualifies under federal law and the laws fo most states. You may have a "household hazardous waste" center in your area. However, if I were you, I'd simply add a relatively small amount of the gas to each tankful. In this manner, I don't think that it will cause you any problem, you'll get rid of it conveniently, and you'll even get some value out of it. You might want to add some gasoline "stabilizer" to it which you can purchase at auto parts stores. Some octane boost might help, too. This will add back some of the volatile fractions which may have escaped and it will "fortify" the octane which has also degraded. However, DO NOT use any gasoline in which there is noticable sludge or varnish. That will have to go to a hazardous waste facility.

[Duke W.]

Re: C2 - What Chemical chg makes for bad gas?

In vented systems like our old Corvettes the volatile, high octane components can be lost to vaporization, which can lower octane and cause detonation.

Really old gasoline can also react with oxygen to form solids, which are usually refered to as "gum and varnish" that can coat fuel system components.

Commercial gasolines have stabilizer additives and have a nomimal shelf life of about one year, but gasoline kept in sealed containers at no more than 60F will last much longer. The colder the storage environment, the longer it will last. For infrequently driven cars the gasoline should be either consumed within a year or removed and used in another vehicle and replaced with fresh product.

The tank should be kept full during winter or other storage periods.

It's usually not a problem to blend old 'stale" gasoline with new gasoline in ten to twenty percent proportion in order to consume it, which is both the simplest way to dispose of it, and at today's prices, the most economical.

Duke

[Tom D.]

Thanks Joe - Thanks Duke *NM*