I have a car that I’m storing for someone–drive it occasionally on the highway, etc but the gas will be in it a long time. Requires premium. I will be using Sta-bil too. My question is whether it is worth paying about 50 cents a gallon extra to get ethanol free premium for this car. It will probably take about 5-6 months to empty the tank again.
I would.
Why Fill It ?
Put gas in a few gallons at a time and replenish it. That way the gas won’t get old. Keeping condensation out of the tank isn’t the problem now that is once was when fuel system vented to the air. I have stored cars with lots of gas and little gas and haven’t had any problems.
CSA
+1 to @texases
Yes, by all means.
+2 for texases.
+3 @texases
You want to fill the gas tank.
The fuel systems on today’s vehicle are still vented.
The venting occurs when you remove the gas cap and add fuel to the gas tank.
When adding fuel to the gas tank, the fuel flowing down the filler neck creates what is called a venturi effect. This forces air to enter the gas tank which then pressurizes the gas tank which forces the fuel vapor into the carbon canister.
So if you only put a couple gallons in the gas tank, the air along with the moisture that was forced into the gas tank will take up the rest of the volume.
Tester
What kind of car are we talking about? Most cars in storage do better just left alone…
If the tank must be refilled every 6 months the vehicle must not be in storage.
I last drove my truck in May, when I take the cover off I expect the fuel level to be the same as when I parked it.
Absolutely. That’s what I put in the car that barely moves.
If you’re only talking 5-6 months, I would not even bother with fuel stabilizer.
Is there general agreement that gas (top tier) is good for 5-6 months without stabilizer?
For 5-6 months I wouldn’t even bother with stabilizer either. Just fill the tank to minimize air volume in the tank.
Is there general agreement that gas (top tier) is good for 5-6 months without stabilizer?
All gasoline will be good for 5-6 months without fuel stabilizer, Top Tier or not.
Top Tier gasoline has nothing to do with how long the fuel will last, or with anything else anymore for that matter. Top Tier designation is an old standard and doesn’t mean much anymore. All major fuels are rated Top Tier these days.
About 10 years ago, GM, Toyota, Honda, and BMW (and several others since then) came to the conclusion that the federal standards for the additives in gasoline were insufficient to provide their engines with the necessary detergency needed to help prevent carbon buildup. So they came up with a higher standard for gasoline, and any fuel that met these requirements was given “Top Tier” designation.
Today even bargain-basement and discount warehouse brands are Top Tier.
All gasoline will be good for 5-6 months without fuel stabilizer, Top Tier or not.
I agree…I’ve never had a problem with gas left in a gas can I use in my mower. I stop mowing around middle of Oct…and my first mow is sometime in Apr or May
I agree… but I put a bit of stabilizer in my snowblower gas anyway. I’m hoping to go for a winter without snow. Or two winters even. I’m hoping the gas has to sit in the can for a long time. 
I leave the mixed gas for my chainsaw & weed-eater sit over winter & use it the next spring with no obvious ill effects . I do like to run those engines dry before storing though . I also run my generator dry because I never know how long it may sit before needed . I’ve had it several years & when needed I fill it with fresh gas & it always fires right up & is good to go . None of the above have metal tanks which might be a different story . My gas containers are also plastic .
I’m hoping to go for a winter without snow.
Move to Seattle. Although to be fair it did almost snow twice last winter.