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When I store for the winter - should I go with a full tank to keep more moisture out (It is in a heated underground condo stall) or partial tank and fill it up in spring with fresh fuel so I would have a smaller stale fuel ratio? I know I sound like a rookie but I have never stored a car for the winter before.
 

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Full fuel tank of ethanol free gas with fuel stabilizer would be the best bet (if it's just through winter you don't absolutely need fuel stabilizer).
 

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I switched to ethanol free and my engine thanks with me steady lows and smooth highs.

Always store full tank ethanol free to combat condensation. Try and drive it no less than once every month to keep things lubricated and charged. If you haven't, invest in battery trickle charger.
 

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Well the car is gone but, A full tank is better as it lowers possible condensation, No ethanol only gas here so a bit of seafoam always went in tank,.
As to tires, raise infaltion but I use to raise the car a bit with jack stands to take off some of the weight but not completely ( prob not needed ) as the car sat from dec to march.

As a PS... trying to get a new fun car is still a bitch !... many not taking special orders AND when I found one car that fit the needs the dealer want a 4K surcharge ( told him to stuff it , wife and I can wait )
 

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I store mine with the tank at 1/4 full. In my judgement, the extra air does not make any significant difference in the amount of condensation. Air goes in and out of the tank (through the charcoal cannister / EVAP system) based on changes in temp and Barometric pressure, and that is hardly effected by the amount of air in the tank. Also note that an intact EVAP system reduces the amount of ambient air that gets in your tank during storage. The benefit of a less full tank is that in the Spring I can fill up with fresh fuel right away instead of running a whole tank of 3-month old fuel. Also, I prefer to store with E10 because it will keep any condensation in-solution, which is preferable to letting the water settle to the bottom of the tank. I also store with the car up on 4 stands and in a sealed bag like CarJacket or Rhino shelter.
 

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...Always store full tank ethanol free to combat condensation...
Ethanol free fuel promotes condensation. It forces all water in the tank into the air, where it can condense and collect in the sump. One of the advantages of ethanol is that it allows water to dissolve in the fuel, where it will eventually be removed by use. Before ethanol fuel, we had "dry gas," which was just a bottle of alcohol that you would periodically dump into your tank to remove water before it stalled your car.
 

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This sounds great until you realise that in most cases, fuel with ethanol already has a lot of moisture dissolved in it from storage in the underground tanks at the fuel station. Then when you fill your car and the ambient temperature and humidity changes, some of that water can condense back out of the fuel onto the inside of your tank!
 

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Having a full tank lowers the non-wetted surface area inside the tank where condensation can form. That is the reasoning behind it.
Condensation forming in a tank during storage is not a function of non- wetted area, but primarily a function of the amount of air that gets exchanged during the storage time due to changes in barometric pressure and temperature. The EVAP system lets a little bit of pressure build up before it vents to the intake manifold and allows some vacuum to build up in the tank before drawing any outside air in. I am not sure which case would exchange more air with changing temp and baro, near-full tank or near empty since the tank itself shrinks with temp, and the fuel has a coefficient of thermal expansion and so do the fumes and air in the tank. Then there is the incompressibility of the liquid fuel to consider compared to the compressibility of the air in the tank. It's a complicated science exercise to solve for both the case of changing baro and changing ambient.
 

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Any source I can find online or from the vehicle manufacturer recommends leaving the tank at least 1/2 full during the winter if you are driving the car or all the way full for winter storage. But you do you.
 

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... I am not sure which case would exchange more air with changing temp and baro, near-full tank or near empty...
I think that the barometric pressure and the vapor pressure of the fuel will be the only significant factors. Pressure swings will be orders of magnitude greater than any thermal expansion effects. The more empty space in the tank, the more gas can be exchanged when the valve decides to open.
 

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Back in the 70's I worked at a gas station and stuck the gas storage tanks every night. I believe they where 10,000 gal tanks, maybe 15000 gals. There was always water on the bottom of the stick. I expect the ethanol in current gas would absorb what ever condensation gathered in the under ground tank and it would never register when sticking a storage tank today. I don't consider 3 month old gas to be "old" but it has been a very long time since I have experienced old gas.
 

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I stopped thinking about it on all of my cars for the most part. I just unplug the battery, put a cover on it, and come back in a few months. December to March isn’t that long. I just got my first direct injected car this year so I may treat that a little differently, start it up every few weeks and let everything get up to temp to keep the injectors in shape. Even that is probably not necessary though.
 

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I think that the barometric pressure and the vapor pressure of the fuel will be the only significant factors. Pressure swings will be orders of magnitude greater than any thermal expansion effects. The more empty space in the tank, the more gas can be exchanged when the valve decides to open
I stopped thinking about it on all of my cars for the most part. I just unplug the battery, put a cover on it, and come back in a few months. December to March isn’t that long. I just got my first direct injected car this year so I may treat that a little differently, start it up every few weeks and let everything get up to temp to keep the injectors in shape. Even that is probably not necessary though.
When you do that on a cold day, you get the coolant hot but you will not get the oil hot enough to drive off the accumulated water. What you really accomplish is adding a few tablespoons of water to the sump. Winter Storage – Roth Automotive Science
To protect the injectors, just add some Stabil to the last tank before you store it.
Dave
 

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Full or partial fuel tank: Do what you wish, but most sites for long term vehicle storage state to keep the tank full, with a fuel storage additive (Stabil). So what is long term? Never seen it defined. However, most vehicles stored “long term” may or will have fuel system issues. The Stabil isn’t only for the tank, it also protects the hoses/tubes and injectors. After I fill my tank and add the Stabil, I drive a few miles to insure my “modified fuel” goes through my entire fuel system. I’m a “sold” person! Never had an issue, but my storage is only for about 4 months, so maybe my storage term isn’t long enough to create issues.

What do people do with rarely driven old or rare cars, probably the same as people here - wonder what to do or nothing or leave it up to their servants. Museum pieces are probably kept with empty fuel systems, for safety/insurance reasons.

As for purchasing a heavy or non-ethanol fuel, I’d have NO idea where to find that or if it’s even available in my area. At the end of the day, don’t forget, it’s still a Toyota that (almost) never dies!
 
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