I see differing opinions on the forums regarding this issue. I'm only driving my car one to two times a month at the most (car sometimes sits for a month at a time) and my concern is about the gas going bad and the consequences of that to my engine. One thread said with premium gas it's not an issue. My questions are:

1. Will I have any issues with the gas going bad if my car sits for 3-4 weeks at at time?
2. Should I always keep a full tank as several of the threads suggest to limit evaporation?

Thanks for your help.

 

Using my experience with boating...

1) With ethanol in the gas, even just E10, the fuels ability to stay mixed with the water particles in the fuel and air is greatly reduced. The ethanol will actually absorb moisture out of the air. If you are in an environment that is humid the gas will attract water, and the longer the fuel sits, more water will separate and settle at the bottom of the tank. This is very bad! I have had pretty good results with E-ZORB in preventing this from happening.

http://www.defender.com/product.jsp?path=-1|311|302335|531412&id=725700

Sta-bil also has a new product that is Sta-bil with the water absorber combined. If you're truly worried, try this.

2) When storing a boat, especially a diesel, it is important to top off the tank so that there is no room for condensation. This leads to water in the tank, which itself is bad, but also allows the growth of biological crap! But this is over the course of several months during the winter when the boat is not used. This should not really be a problem in a car stored for a few weeks.

As a side note, E10 gas sucks! In the 3 gallon gas tank on my RIB, I can go about a week with out water contamination. On top of that, the ethanol is corrosive and ate away at the inside of the fuel lines, which then gummed up the carburetor. Last summer this all happened mid June. After replacing the fuel tank and lines, cleaning and rebuilding the carb 3 times, the problem has not been corrected. Now I think it might be the reed valves in the crank case which may need to be changed! I have not been able to use the boat since June, which killed my water skiing/tubing fun!

I also have friends that had worse problems! Built in fiberglass fuel tanks are being eaten away. So now you have to pay to have new tanks made and installed, which could be a big job. And if any fuel leaked out, you wasted fuel, which undoubtedly leaked into the bilge and out through the bilge pump. If some ***** caught this, you could get a huge fine from the CG (even for just one little drop) and have to pay for clean up.

And all this because our "representatives" in the government have their hands in the pockets of Corn growers. Ethanol is no good! Increased fuel consumption, extremely damaging to fuel systems, and it takes more energy to produce ethanol then what you get out of it. I could go on and on!

 

Very simple. Gas loses it's light ends over time. 3 to 4 weeks is nothing. Keep your gas tank full to minimise vapour space & reduce chances of water condensing in the tank with temp changes. Modern Benz systems are very tolerant of hydrous alcohol.

 

you have NOTHING to worry about in 3-4 or even 10 weeks...

 

Thank you for your responses and help. It always amazes me that we have this kind of wisdom available to us for nothing. Just look at the three people who responded - I am a boy among men.

 

3-4 weeks yes, as long as your car is not kept close to the water or where you have constant high humidity. But if you're stuck using E10, I would not go 10 weeks ever without putting something in there.

I should have mentioned that I'm only talking about E10 gas. Regular gas can sit for a month with no problem what so ever. Pretty much every car made since 1990 has a fuel system that can handle E10 as far as corrosion resistance. That is a problem for boats that is just starting to pop up as more and more states are mandating the use of E10 even for boats, which are not designed for E10. But E10 gas has major water problems. In the marine environment, and anywhere with constant high humidity will cause this. Most people never see it because they run their car often enough that the fuel stays well mixed and any passes through the engine in small enough quantities to never be a problem. I have had problems with my car after sitting for 5 weeks, before I experienced all the issues with my boat. The car ran real crappy, and a fill up and a bottle of dry gas (to absorb the water) fixed it.