Old Gasoline

[Christopher R.]

My '62 has been sitting with a full gas tank for about 6 years. The gas was treated with Sta-Bil then. Sta-Bil says that it is good for 1 year. In preparing to get the car running again, I am rebuilding the carburetor among other things. The idea of running 16 gallons of old gas through my painstakingly rebuilt carb is unpleasant. So, I am thinking of pumping out the old gas and replacing at least most of it with new gas.

What to do with 16 gallons of 6 year old gasoline? I live in the city on a small lot. My power mower uses about 1-2 gallons per season. I thought I might put a few gallons at a time in my everyday car. But this car (Audi) has modern fuel injection (Bosch CIS-III). I have never had any trouble with this system, and I would like to keep it that way. I understand carburetors, but not fuel injection. How fussy are modern fuel injection systems to bad gas. Of course, I would dilute the old gas with new gas.

What is the consensus on the trade-off of running straight old gas through a carburetor versus running diluted old gas through a modern fuel injection system? What do old car people do with old gasoline?

[Jeff Gunn #29146]

Re: Old Gasoline

Funny you should mention this, I just got my '74 back from the paint shop with a tank full of two year old gas. I don't know the answer to all your questions, but I'll tell you what I plan to do. I am going to put about 4 or 5 gallons per tank into my '99 GMC pickup. It is still under warranty, so hopefully if I do mess something up it will be fixed by GM. But I really think that old gas will just lower the power level of the vehicle a little, since it has less volatility, less energy left in it. I am not using the right words here, but I think you get the idea. I am also going to pour some of it in the expansion joints of my driveway and kill those damn weeds..


Jeff's '74 Corvette Restoration Project

[Iron Duke NCRS #22045]

Re: Old Gasoline

According to oil company researchers I've talked to gasoline has a shelf life of about one year. Sta-Bil should increase that, but they don't make much of a claim. Gasoline will eventually begin to break down and form "gum and varnish" which are basically solids that precipitate out and form deposits on interior fuel system surfaces. The rate of breakdown is a function of storage temperature, and the higher the temp., the faster it will break down.

I'd suggest draining all the fuel including the fuel lines into jerry cans, and, if possible, check the fuel tank for deposits and/or corrosion. It would probably be best to remove the tank for inspection. In particular, I've found the wire wind on the gage/sending units tend to get deposit buildup, which can affect gage accuracy/readings, but it's just been a matter of cleaning them off with acetone. At today's prices it would be nice to get some value out of the old fuel, plus there's the disposal issue. I think consuming the fuel by adding a few gallons to your Audi every fillup sounds reasonable. If there are any microscopic suspended solids they should be picked up by the fuel filter, so at worse, I would only expect a clogged filter, but it probably won't happen. Modern FI cars have good filter capacity to protect the close tolerance parts in the fuel systems. Just be sure to change the Audi's filter when it comes due for it's next renewal. I have a CIS III system on my Merc, and I change the filter every 30K, and it's a pretty good sized filter.

I've had good luck storing cars for up to about a year with full fuel tanks and no stabilizer. I'd add the stabilizer for up to two years. Beyond that, or for indefinate storage, I would completely drain the fuel system and flush it with mineral spirits.

Duke

[Iron Duke NCRS #22045]

P.S.

I hope you drained your cooling system before storage. In any event, drain it now, and I'd suggest mutilple cold and hot flushes with water until all traces of the old coolant are removed, then fill with a 50/50 mixture of Texaco Extended Life antifreeze (Dexcool) and distilled water. Also, flush the brake system with at least on quart of fluid.

Duke

[Joe L.]

Re: Old Gasoline

Chris-----

In 1974 during the "fuel crisis", I stored two 5 gallon containers of unleaded gasoline away for an "emergency". Well, the "crisis" didn't last too long and the gasoline sort of got forgotten. In 1986, or so, I decided that I needed to do something with it. I inspected it carefully and found no evidence whatsoever of any precipitation, gum, or varnish. So, I put the 10 gallons into my Corvette's tank and filled it up with fresh gas. It ran PERFECTLY; no problem whatsoever.

If I were you, I think that I might siphon the gas into jericans, inspecting it as you do. If there is no evidence of precipitates, gum, or varnish(and I don't think that there will be) put 5 or 10 gallons back in the tank and fill with fresh gasoline. I'll bet that you'll have exactly the same results as I did. Then, "get rid of the rest" the same way.

[bill]

Re: Old Gasoline

Chris

Almost all communities, at least on a county level, have household hazardous waste (HHW) collections a few times per year. The company I work for is contracted to do this work in many areas of the country. I suggest you call your local county officials and ask. The only requirement is that you reside in the area which is sponsoring the event. Personnaly, I wouldn't trust 6 year old gas in any quantity. Most of the companies which do this sort of work are happy to return your containers to you if you ask. If you find an HHW in your area, you can also dispose of the other accumulated chemical junk from the garage. Good luck

[Iron Duke NCRS #22045]

Preventing oxidation is the key

Gum and varnish are basically oxidation reactions, so if you keep oxygen away from the fuel it will remain fairly stable. If a fuel can or fuel tank is full, there is very little available oxygen. The worse thing you can do is store a car with a near empty tank. There will be plenty of oxygen available for reaction, so the best way to store is either with the tank full or completely empty and dry.

Duke

[Dave #24235]

Re: Old Gasoline

If you live in a town with poor people, I am sure you can find someone with an old car or pickup who will be glad to have the stuff. If you live in Beverly Hills, you're on your own. - Dave

[Everett "Not a Chem - E" Ogilive]

Re: Old Gasoline

I'm not a chemical engineer, but I studied fuel distillation curves a bit while trying to learn about racing fuels for my car. It seems that the front-end, or "light" components of the fuel, are the ones that come out (evaporate at a very quick rate) any time you open the lid to the can or the tank. This leaves behind the more heavy components of the fuel, and the more often this happens, the greater the likelihood of varnish and deposits forming. If Joe's old fuel still looked good after all those years, perhaps it is because it was kept sealed for that time. After I read about the light components, I never open my gas cap anymore. Not even to add gas... Now the car just sits there.