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Old gas in tank Q?


CaliAuto909
05-16-2008, 09:52 AM
I've got a question about gasoline sitting in the tank too long. I wanted to know what any of you classic car AF members would recommed, being that alot of you have probably had to revive a vehicle from sitting for long periods.

1. My vehicle has been parked for 2 years w/ a 1/4 tank of gas, and I wanted to gather some facts on the effects of gasoline sitting in a tank for that amount of time, or even longer.

2. Also, what procedures, and/or treatments (if necessary), should I do to revive my fuel system, and also revive my tank, so that I'm not burning a bunch of pollutants in my engine?

MagicRat
05-16-2008, 07:58 PM
Is this the '88 Integra shown in your profile?

Have you tried to start the car in the past 2 years?
There may be other issues that require attention.

Your biggest concern IMO is condensation. A 1/4 tank leaves a lot of air space for temperature variations and humidity to accumulate moisture in the tank. Moisture (water) and gas do not mix. The water is heavier than gas and settles at the bottom of the tank, which may produce rust which can quickly clog fuel filters leaving you stranded and/or lead to a leaking tank.

If you want the car to function reliably, lift the car, remove the tank, remove the sender unit, drain the old gas, inspect the inside of the tank for rust (repair or replace tank if necessary) and reassemble. Refill with new gas. Safely dispose of the old stuff.

Water aside, two years is not long enough to allow gas to deteriorate much.
Some of the more volatile components of gas may evaporate, which may affect the performance of the gas, such as more knock and ping, more deposits in the engine, etc. However, IMO if you were to simply fill the tank with fresh fuel, the existing gas would be mixed and diluted and likely could be burned in the engine just fine.

I regularly store my cars for 1 - 4 years between road trips. I always store them with a full tank to prevent condensation, but the cars always work just fine on the old gas I leave in the tank. I do drain the carburetors though, and I do start and run them several times a year to avoid other problems.

Personally I have used very old gas in engines without difficulty. I once used 10 gallons of 18 year old fuel without difficulty, and have used 5 - 10 year old gas on many occasions without a problem.

In my experience, after about 3-5 years, gas seems to change in that it smells different, more like varnish and less like gasoline. However, it still seems to work fine. I am not sure of the actual chemical changes that are causing this change in odour.

'97ventureowner
05-17-2008, 01:19 AM
To add to what Magic Rat posted , I read an article a couple years back which discussed gasoline. The article stated that the gasoline that is produced today is a lot different than that , that was produced years ago. ( Part of the reason I believe has to do with additives and pollution abatement to work better with modern engines.) One of the points that the article discussed was that the "shelf life" of this newer gas is a lot less than the stuff that was made years ago. They said that gas today starts to go bad in as little as thirty days. I have noticed this not in as much as affecting a regular automobile, but rather small engines. There were things one could do to "extend" the life such as only storing as much as you can use in a short period of time, keeping it well sealed, and using a fuel stabilizer. I regularly use Stabil in my small engines when I store them for the winter and have no problem starting the engines come Spring. I have yet to use it in a car though because I haven't had the need but I believe it would work as well for storing a vehicle. In those instances where I didn't use a fuel stabilizer in the past few years, I have noticed that the engine is hard to start possibly because the gas has already started to break down and "gum up" the carb. A way around this I have found was to add some fresh gas and let it sit for a day or so and most likely, the engine would start up after that addition of fresh fuel.I believe an additive in the gas put in at the time of processing either dissolved enough of the varnish , or gum, to allow the engine to start, or diluted the old gas enough to create better starting conditions.

MagicRat
05-19-2008, 12:45 PM
As noted above, old gas is a bigger problem for small engines.

Small engines are a bit different than cars. They are more susceptible to the problems of bad gas due to the much smaller components and orifices found in their fuel system.
Older fuel can see their lighter, more volatile components evaporate. The gas becomes slightly more viscous and cannot be sucked through the tiny metering jets in a small engine carb, especially when the choke is open. Therefore, the small engine will not run. Put the same gas into a larger engine, especially one with EFI running under pressure and the fuel works well.

'97ventureowner
05-19-2008, 02:04 PM
As noted above, old gas is a bigger problem for small engines.

Small engines are a bit different than cars. They are more susceptible to the problems of bad gas due to the much smaller components and orifices found in their fuel system.
Older fuel can see their lighter, more volatile components evaporate. The gas becomes slightly more viscous and cannot be sucked through the tiny metering jets in a small engine carb, especially when the choke is open. Therefore, the small engine will not run. Put the same gas into a larger engine, especially one with EFI running under pressure and the fuel works well.
Actually my post above was geared towards carb equipped cars,( most "classic cars" as this sub forum implies are carbureted.) I've had issues with my older, carb equipped vehicles that were in storage for a length of time, getting them started, (especially if I didn't use a fuel stabilizer.) I treated them similarly to the small engines that I have in which I added fresh gas and let it mix with the old gas and then used the fuel pump to draw this mixed gas to the carb, where I let it sit overnight and many times had success in getting it started. I was told that there are additives in gas that help dissolve gum and buildup caused by old gas and letting the fresh gas sit it the carb did it's job to an extent. Sorry if my post was misconstrued,it's not everyday I encounter a fuel injected vehicle in the classic car forum :lol: I do agree that fuel injected is much better if you're storing the car. I rarely have an issue starting a vehicle that has sat with old gas but is fuel injected.:grinyes:.

72chevelleOhio
05-20-2008, 04:37 AM
Sta-bil brand.
If i forget and leave something sit without it, I usually add a fuel cleaner and fill up with new gas. Then run another tank with fuel cleaner through it and it should be good to go.
Although like MagicRat said, if the gas smells more like varnish and less like gas then I would drop that tank definitely. Probably blow some cleaner through the lines and spray the carb down too.

CaliAuto909
05-22-2008, 09:15 PM
First off, I just want to thank those who responded with facts and recommendations.

[QUOTE=MagicRat]
Is this the '88 Integra shown in your profile?

Have you tried to start the car in the past 2 years?
There may be other issues that require attention.

If you want the car to function reliably, lift the car, remove the tank, remove the sender unit, drain the old gas, inspect the inside of the tank for rust (repair or replace tank if necessary) and reassemble. Refill with new gas. Safely dispose of the old stuff.
QUOTE]

As a matter of fact, it is the the 88 Integra listed in my profile.

I haven't run the car within the 2 years it's been sitting......'been kinda lazy about it, but now I'm getting ready to revive it and use it again. Aside from after inspecting the fuel tank, I've got to lube and manually crank the engine, to break it loose, before I cold start it.

I opened the filler cap and the fumes don't smell like varnish. Smell's really stale to no fuel smell at all. I think I'm going to go ahead and drop the fuel tank and visually inspect it, within the next week.

I'll let you guys know.

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