Ethanol in "lightly driven" vehicles

I have a 1999 Ford F-150 with a 4.6l V-8, it has around 78K miles on it. I’ve owned it since new. A couple of years ago we bought a third vehicle so the truck sits most of the time and gets driven only 2-3000 miles a year. It alternates between going on trips with the scouts that can be 30-50 miles away sometimes up to 150 miles away generally towing an enclosed utility trailer of 2500-3000 pounds and trips to the local home improvement center or garden center. A tank of gas can last several months if I don’t go on the monthly scout outing. Given this, and the prevalence of 10% ethanol fuel common at nearly all gas stations these days what is the best strategy for fueling the truck?

  1.  Keep it topped up?
  2.  Run it down to a quarter tank and fill up ?
  3.  Add $20 worth of gas when it gets below a half tank?
  4.  Search out and pay the extra cost for non-ethanol gasoline?

Should I add a fuel stabilizer to the tank given ethanol’s tendency to absorb water and the fact that I live in hot and humid North Carolina? I had to replace the fuel pump last year, I’m not sure if the lack of driving caused this or the fact that it is 14 years old. Mileage didn’t kill it, but age and inactivity may have. Other than the fuel pump and a couple of other minor issues (ABS sensor, door lock and window switches) it has been a relatively trouble-free truck.

If you can find non-ethanol gas, that’s the best way to go. Otherwise, if you let it sit for more than a couple months at most, toss some Sta-bil in there just before you fuel it.

It generally gets driven weekly, but if I don’t get a long trip in the gas can be a month or two old before I need to refill. There are a few stations that carry the non-ethanol gas, I’m not sure what their price delta is, the one station has one pump with straight regular unleaded while the rest of the pumps have ethanol blends.

Stabil makes a fuel stabilizer especially for ethanol gas. It is marketed primarily at the marine market, but I see it is sold in most auto parts stores too. Instead of red, it is blue. You should add this stabilizer every time for buy gas for this little used truck.

Thanks UT and Shadow.
I’ll get some of the blue Stabil and put it in the next time I fill it up especially if it is going to be awhile before I burn through that tank. Any thoughts on keeping the tank full versus letting it go down to a quarter before refilling?

No need to keep it full. That might make Sta-bil accounting difficult anyway.

So run it down to a quarter or so, add the Stabil and refill. Repeat as needed.

Yep. To clarify my original post, I meant letting the gas sit in the tank without driving enough to use it all.

@Sparky617, yes, that’s what I would do. Pick a level you are comfortable with and refill when you hit that level. Then you always know how much Sta-bil to put in.

Can we get one thing straight. Fuel stabilizer is a generic additive that keeps gas from breaking down but, it does nothing for the ethanol problem. That is a separate issue. Using Stabil FOR ETHANOL or Marine grade as written on the label, HAS NOT HELPED ME either as much as hoped. Stabilizer in general does not stop the water separation during long term storage.

There are other additives I am presently trying that so far, seem to work but it’s such a slow insidious process, you can’t tell until accumulated affects occur, sometimes over a few years. Try additives from a Marine Supply place as gasoline in a marine environment is the toughest to deal with. Let me repeat ; regular Stabil Or other generic stabilizers and even Stabie for ethanol does not work well for the ethanol separation.

So, if you just throw a gas stabilizer in, prepare to be disappointed. Don’t trust VIP or other discount store additive sellers to know what they are talking about. Small engine repair people have been dealing with it for years including marine engine repair shops, can give you the best advice.

It’s impractical in a seldom used cars, but I drain the gas and run ethanol free gas through the system in all my small motors before storage. The best thing ! Don’t vote for anyone who supports continued use of ethanol in gasoline if your cars sit or you have small engines.

I should add, the truck is going to get a bit more usage now, our teenage daughter has her license now so I may have to use the truck around town more often than before she got her license as she’s using the car to get to work and in the fall, school. I still expect a tank of gas to last 3-4 weeks as I work from home most of the time and the office is less than a mile away. So even when I go to the office I usually ride a bike or walk.

Thanks for all the replies guys.