Fuel level in cold weather?

**CharlesW** · 12-31-2008, 05:38 PM

It has always been my policy to keep my fuel level above the 1/2 way point during the general course of driving around town. That way, I don`t have to worry about having to buy gas before I can go somewhere.

In the winter, I try to keep it close to the full mark to prevent condensation in the fuel tank.

My question is;
With the fuel tanks/systems on later model vehicles, (2000 and later, that`s late model to me.

), is condensation going to occur if the tank is 1/2 full?
Or is the fuel tank sealed off from outside air?
If fuel vapors can`t get out, it seems like air/moisture shouldn`t be able to get in.

**Old Pirate** · 12-31-2008, 06:00 PM

Good question, I always use some additive in my fuel when i was up north, but for down here once in awhile I put some STP additive for the same reason. Gas stations have water in their underground tanks to raise the gas up for pumping. Don`t know for sure if they still do that. But for condensation in newer model car`s not sure if one needs it or not. To stay in the safe side i do put some type of additive it my tank........just my 2 cents.........

**Bunky** · 12-31-2008, 06:18 PM

I never put in any additives and never worry about fuel level. I have felt some "batches" of gas were better than others but never seen any real link.

**CharlesW** · 12-31-2008, 06:28 PM

Actually, my question is if my cars will have moisture condensation inside a partially full tank in the cold weather. Cold meaning from 40 degrees down to 0 degrees. Sometimes 10 or 20 degrees below 0, even.

I know it could be a problem years ago, but I don`t know if the later years allow that moisture laden air to enter the tank.
Anyone know?
I`ll probably ask my mechanic in the next week or so since he will probably know.

**CharlesW** · 12-31-2008, 06:50 PM

A simple Google search, (Which I should have done to start with

), came up with a lot of information. The general consensus seems to be that the little condensation that does form does more harm rusting the inside of the tank than it does to the gasoline.
That makes me think that continuing to keep the tanks relatively full would still be a good idea.

**black bart** · 12-31-2008, 09:06 PM

Originally Posted by CharlesW

A simple Google search, (Which I should have done to start with

), came up with a lot of information. The general consensus seems to be that the little condensation that does form does more harm rusting the inside of the tank than it does to the gasoline.
That makes me think that continuing to keep the tanks relatively full would still be a good idea.

I agree even with a sealed system if the temp drops the air in the tank will cool and condense so water will form.
Less air space means less water.
Some cars like my Corvette has a rubber liner in the tank.
I always put a can of heet in my tank every winter when it gets cold to make sure any water does not freeze and cause a problem.
I have done this for years and have never had a problem.

**jaybs02** · 12-31-2008, 09:13 PM

I remember having to put in "dry gas" to help remove the moisture so that the fuel lines wouldn`t freeze up. Now with the addition of ethanol and the newer fuel systems I don`t put in additives in my car, but I still have an anti-gel put in the tanks of my trucks at work.

**baker** · 01-01-2009, 06:30 AM

Never had any problems like this and I am in a cold climate in the winter, Nova Scotia Canada. Damp too.

**CharlesW** · 01-01-2009, 08:05 AM

Originally Posted by black bart

Some cars like my Corvette has a rubber liner in the tank.

Wouldn`t the condensation still form on the inside of the rubber lining? At least you wouldn`t have the rust problem and I don`t think the "water in the gas" is as much of a problem as it is thought to be.

Originally Posted by jaybs02

I remember having to put in "dry gas" to help remove the moisture so that the fuel lines wouldn`t freeze up.

That used to be standard procedure for many people in my area,too. I haven`t done it for years.

Originally Posted by baker

Never had any problems like this and I am in a cold climate in the winter, Nova Scotia Canada. Damp too.

You really wouldn`t know if you had condensation iinside the tank unless you looked, would you?
I don`t think the water is likely to be enough to contaminate the fuel in a vehicle that gets driven fairly regularly. If the gas sets in the tank for a month or two, it will probably go bad anyway. I do use Sea Foam or Sta-Bil gas stabilizer in the fuel tank of the Corvette. I drive it year round, but only on the days that there isn`t any salt slush on the streets during the winter. Some years, those days are few and far between.

Many stations, maybe all, put some cold weather additives in the gas in my area. I would almost bet the same thing happens in many/most cold climates, including Nova Scotia.

**black bart** · 01-27-2009, 06:10 AM

Last week we had a few days of real cold weather.
We had to go to town and I told my wife i bet we will see a stalled car it was -10f
In the 7 mile trip to town we saw 2 vehicles stalled no doubt it was due to fuel line freezing.

Perhaps it would not be needed but every year when it gets cold I add a can of heet and in 60 years of driving I have never had a problem.

The peace of mind of knowing I`m not going to stall in that kind of weather is worth the dollar a year that it cost.

**CharlesW** · 01-27-2009, 08:54 AM

Originally Posted by black bart

Last week we had a few days of real cold weather.
We had to go to town and I told my wife i bet we will see a stalled car it was -10f
In the 7 mile trip to town we saw 2 vehicles stalled no doubt it was due to fuel line freezing.

Perhaps it would not be needed but every year when it gets cold I add a can of heet and in 60 years of driving I have never had a problem.

The peace of mind of knowing I`m not going to stall in that kind of weather is worth the dollar a year that it cost.

There`s still a few cans of Heet on the shelf in my garage.

I used to buy and use that stuff by the case, but I decided it probably wasn`t necessary with the additives in the gasoline today. Since I quit using it about 20 years ago, I have not had any gas line freeze problems. I don`t happen to use the Ethanol blends, but I would think using them would eliminate the need for any gas line anti-freeze products. From my experience, I don`t think I need them anyway.
But, as you say, it`s pretty cheap peace of mind whether you need it or not.

**grisby** · 01-27-2009, 04:19 PM

That used to be a concern of mine(still is in my 72 GS but that isin storage) but since most of the new fuel tanks in cars are some type of composite or plastic material, I don`t get overly upset anymore.

thanks
bill g