that's a good routine to have. its one less thing to think about you know.. im a busy guy. i dont want to be thinking about getting fuel looking at a frikken fuel light. just pump and get it over with.

 

I agree. No disrespect intended to folks who wait until the last possible moment to fill up, but . . . why? It's not like there aren't plenty of gas stations around. I don't understand the point of pushing it so far.

 

they dont want to refuel so often.. even though they like to go to starbucks for their 5min of glory every day. not sure.

 

I wait for the last possible time to regas out of bad habit. Its stupid but I have ran the fit well into the empty and still get about 9.2 gallons into her.

 

I don't necessarily wait until the last possible time...
But I will admit, that I have never just refilled on a specific repeated day or time cycle, regardless of where my fuel level is at.

As long as I have owned and operated a vehicle I have always refueled on some evaluation tied to what the gauge is saying I need to do.

I suppose simply choosing a weekly or bi-weekly "day" and filling on that day is perfectly valid.
But I just have a hard time pulling in and refueling IF I still have what I consider plenty of fuel left in the tank.

 

I thought my GK5 had the smallest tank I had ever come across. If I go by the warning light, then I can barely get 8-8.5 gallons in the tank going from what it claims is bone dry.

I generally practice the "no less than 1/2 tank" method, so it's really not an issue for me. But when my wife drives the car, it's another story. She absolutely loves running the tank dry. It will be interesting to see how long the fuel pump lasts...

 

Yesterday I drove a few miles past zero and only got 8.7 gallons in. And that's going past the shut-off a couple of times. It's annoying to stop for gas more often than necessary (and in yesterday's case I could've saved 20 cents a gallon had I continued to drive another two blocks).

 

I live in a cold climate where in the winter time there is a problem with condensation in the gas tank empty air space. The emptier the gas tank the more air inside and the more condensation might form on the cold walls of the tank. This water condensation would eventually get sucked into the fuel line where it could cause a frozen fuel line blocking gas flow to the engine. To counter the problem we would try and keep the gas tank as full as possible in the winter and in addition add some methyl alcohol when filling up. The methyl mixed with the water preventing it from freezing and allowing it to flow to the engine and be burned off.

Of course with the arrival of gasohol which contains ethyl alcohol the naturally included ethanol does the same job as methanol eliminating the need for any additional additives to regular gasoline. Nonetheless out of habits I learned many decades ago I still tend to keep my gas tank at least half full especially in the winter. Less condensation in the tank also reduces the internal rusting of the tank although with improvements made in gas tank construction this probably hasn't been much of a problem for a long time.

 

Interesting info. Thanks! I always like hearing about different precautions needed in colder climates. You all definitely have a lot more to think about.

 

Isn't almost every modern gas tank plastic of some sort though? I haven't seen a metal tank (discounting aluminum fuel cells) in anything 80's up.

Condensation certainly makes sense however.

 

Yeah they're probably plastic now for weight saving reasons but they were metal back in the 60's 70's 80's when I was going through my first cars. Fairly rare now. Large commercial trucks might still be metal.

 

When it's cold enough for water to freeze, how much humidity is in the air? Is this really an issue?

 

naw, not unless u got less than half a full tank of gas sitting for like a year without stabilizer.

 

Have you ever seen frost form on your windshield overnight in really cold weather? Now imagine that that frost is on the inside of your gas tank. Anyway, as stated not an issue any more in really cold climates because of gasohol.

 

Point taken, but that frost is from lots and lots of air passing over a windshield. The gas tank is pretty sealed so there's no air circulation. The water content in a few gallons of air would be minimal, especially in cold weather where absolute humidity is very, very low.

I'm a pilot and pre-flight includes checking the tanks for any water (there are several drains per tank). I've never had any water in the tanks, although I hear it happens from time to time. Don't know what season or where the water comes from.

 

yeah i also hate the fuel tank design. more on where they mounted it. cant rest my feet below the seats during long drives.

 

Actually a gas tank isn't sealed - if it was you wouldn't be able to draw gas out of it because you'd be creating a vacuum in the tank. The venting built into a tank allows a slow exchange of air which even in the coldest temperatures may create a slow frost build up in the air space of the tank. There's a lot of discussion on frozen gas lines caused by this eg:

https://community.cartalk.com/t/wate...l-filter/59787

 

Of course it's not completely sealed but I imagine the vent is tiny or the gas would evaporate. Or at least there'd be fumes.

My guess is that since frozen fuel lines are rare, the water isn't coming from the air but from the gas station.

 

Don't know what's used now but gas tank venting used to be done through a charcoal canister. The charcoal would absorb gas vapors and that would be subsequently cleared with some kind of a line going to the engine to burn off those fumes keeping the charcoal from becoming too saturated with gas.

As far as water coming from the gas station, how exactly how does the water get into the storage tanks in the first place?

 

flood plus corroded tanks or piping.. or just heavy rain + corrosion