Mexstan

Anybody have any advice on whether to store a vehicle for a long term with a full tank of fuel or almost empty? I know the theory about storing a fuel tank nearly empty and leading to possible condensation when it heats up during the day and cooling off at night. On the other hand, a full tank of fuel may not collect condensation, but if stored long enough, the fuel will deteriorate to some extent.

In 'the old days' diesel stored for long periods of time did not deteriorate significantly, but apparently today's new formulas can start to deteriorate in as little as 28 days.

So which is better in the long run, store it will a full tank and then be forced to run the tank out on "bad' fuel, or take a chance on the condensation and fill the tank up when the vehicle comes out of storage?

oliver foster

How long are we talking for storage?
Dry or humid location?

Mexstan

6 - 12 months. Humidity 20 - 50%, mostly less than 40%. Outdoors storage.

oliver foster

Every one of my trucks, other than my two '95s, sits for 6 months every winter as I will not drive them in the salt. My plow rig sits all summer with the same fuel in it, even if I use it slightly around the property for lumber moving. My dump truck has not had a fill up in almost 3 years as I just use it around the property for firewood.
I have never had a problem with diesel sitting for that short a period of time.
I have also bought several trucks that have not had a fill up of fresh fuel for 2-5 years without issues.
I would think water from condensation would be more of a worry than the fuel "aging".
The only issues I have seen is the rare algae growth in a tank with water in it for long periods on time.
My vote is fill it up and not worry about it.

Mexstan

Thanks Oliver. Unless someone else chimes in with some other info, that is what I will do. In the past have let my truck sit for up to 3 months with no problem.

Busboy

I have a 46 year old gas 4x4 that doesn't get driven hardly at all and all I do is put small amounts of fuel into it keeping the fuel fairly fresh, the last fill up was probably over 25 years ago. At the farm we have tractors that don't move for most of the year both gas and diesel and I do the same with those just small amounts of fuel, 5 gallons, then there is room to top off with fresh fuel. Only had a problem about 45 years ago with summer diesel gelling at -35, that was before I knew there was such a thing as WINTER diesel.

oliver foster

That is how I fill my chainsaw. Just a little bit when I need it. I then try to run it out of gas when I am done. The new gas is total carp though.
I don't find my Diesel engines give me the same problems. The new gas is part of the reason I have been converting every truck I own to Cummins power.

Mexstan

Thanks for the replies so far. The reason that I asked the question in the first place is that I had read that the new low sulpher or ULSD fuels appear to deteriorate faster than the older formula fuels. Not sure if this is a fact or not.

If I do need to store my truck will do what I did in the past and that is to just fill the tank.

Busboy

I have started using only the best grade of gas in all my small engines, the "premium" gas doesn't have any ethanol in it and is much more stable, since I started doing that I've had no problems with my small engine equipment that often doesn't get used for long periods.