Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Fuel additives


It can cause varnish which can cause hard starting.

If varnish is formed then it’ll have to be removed. Most good gas cleaners will remove it.

It needs fuel stabilizer [b]before[/b] it is put into storage.

If it has already been in storage for 3-6 months, it is too late for an additive to help. Just try to siphon the old fuel out and fill the tank with fresh fuel and hope for the best.

If the car has not yet been put into storage or has just been put in storage, go to Walmart or an auto parts store, buy some fuel stabilizer, and follow the directions on the bottle. If you don’t already have one, it would help to have a long neck funnel for putting fuel stabilizer in the tank.

It’s also entirely possible to have gasoline less than 6 months old in which an additive (Stabil for instance) has been used to go bad anyway.

Just got through with an episode of this a couple of days ago and the gas in question was nowhere near 6 months old.

A year or so ago I had an instance of a project car of mine refusing to even cough and the gasoline in that one had gone stale (with Stabil) in only 4-5 months.
After draining I dumped some of the gas on the concrete, threw a match on it, and it didn’t even flash up. After about 6-7 seconds of a burning match it slowly started burning; much like you might see with diesel, etc.

I’ve never heard of fresh gas going bad in that short a period of time. (I reckon anything is possible though)

I am however, wondering if some gas outlets that don’t have a reasonable turn over of gas could shut off one underground tank until the other was used.

If business is slow it would take time to empty out the first one leaving the closed one to go stale. Possible?

Did you find out why the gas went stale so fast? 4-5 months isn’t long.

I have been using Stabil in my '02 Tahoe (but not the '04 Toyota Matrix), snow-thrower and lawn tractor for the last few years, but prior to that I went sometimes 6-7 months and was able to use the old gas.

One thing I have found while talking to friends is some people who do use a fuel stabilizer do NOT drive/run the vehicle or machine long enough to push the stabilizer through the entire fuel system.

Past the injectors or carbs.

6 months should be OK without doing ANYTHING. Stabil works fine for me out to 2 years…I have seen NASTY gasoline after 2.5 years. Temperature seems to make a big difference. In a hot climate, gasoline seems to degrade MUCH faster than in a cool climate. Boats, because of the deadly mix of gasoline, ethanol and water, have the MOST problems.

Good points there, Caddyman.

As you should know by now

  • 6 months should not be a problem.

  • The only additive that works needs to be added before the storage. It prevents problems not fixes them.

    BTW it would help if you turned off the CAP LOCK key!

I have no idea why gasoline has deteriorated so quickly but it’s happened 3 times to me in the last couple of years with the latest 2 month episode being by far the worst example.

And no, the gasoline was not contaminated in the 2 month incident because the fuel tank had been removed from the car and cleaned beforehand along with clearing all of the fuel lines and adding fresh from the pump gas immediately afterwards.
When reaassembled the car ran great. The problems only occurred after it sat for a couple of months and examination of the fuel showed that it not only had a bad flash point it just flat looked and smelled odd.

The only thing I’ve been able to theorize at all is that the gasoline had 10% Ethanol and this may have combined with the extremely hot and humid weather here in OK to change the gasoline characteristics.

At this point, the 2 month old gas has been removed, the carbs and lines cleaned out, and fresh gas added. It runs great now; we’ll see in a month or so what happens.

I have no idea why gasoline has deteriorated so quickly but it’s happened 3 times to me in the last couple of years

Well I have an idea. Where are you getting your fuel? It could be trash fuel. A few stations will buy old fuel. If you are buying the lowest cost fuel in town and from a local brand, I think that might be your problem.

Yes, that could be it. I once tanked at “Joe’s Bait & Tackle” in a remote Rocky Mountain location. The car ran rough, no doubt due to old and/or contaminated gas. Many of the old single wall tanks leak; they may have water leaking in on the top and gasoline out at the bottom.

The gasoline has come from several places. One is a local store/station where I’ve bought most of my gasoline for about 20 some odd years with no problems.
(They also installed new tanks about half a dozen years ago)

The other places I buy from are Cenex and Conoco; usually the latter.