Diesel Shelf Life

SteveInMD · Jun 2, 2005

You are probably right. I'll see how fast we go through it. I was concerned because the sun seems to really heat up the metal tank. I 'm guessing that causes the fuel to oxidize and also to loose the more volatile hydrocarbons.

I did add Power Service stabilizer. Does anyone know how stabilizer works? I always feel like I'm buying snake oil when I buy that stuff. I would think it would have to be some sort of antioxidant (but not so strong that it caused problems with combustion in the engine.) As I mentioned above it would also have to keep the lighter hydrocarbons from evaporating. I don't know how it could do this? Does anyone know something about fuel chemistry?

Dachshund · Jun 2, 2005

Paint your tank with the same "CoolSeal" stuff they use on Mobile Home roofs. Works around here anyhow.

fishman · Jun 7, 2005

I don't know how Powerservice works, but I use it based on recommendations from several knowledgeable people on this board and have had no problems. I think the most important thing it does is bind with the water/condensation, but again I don't know the details.

I also use Stabil in my gasoline with very good results. I've experienced first-hand the results of not using a stabilizer and it is not good. Thankfully it wasn't my own equipment.

Lawnjocky · Jun 8, 2005

I was once told (or read ) a good rule of thumb for fuels is:
2 cycle mix - 1 month
gas - 3 months
diesel - 6 months
If you use stabilizers double it.

I'm sure this is conservitive but it has worked for me. I also learned that rule a long time ago so things may have changed. But safe is always better than sorry.

I did have deisel go bad once and that was 2 times to many. The tractor just barely ran and when I drained it (full tank) the fuel had seperated. I allowed it to set for a day in a clear container. The diesel had a light color (almost clear ) on top and dark on the bottom. There was no water. It was very weird looking stuff. I believe it was about a year old with no stabilizer. The diesel may have been winter mix as well. I've always wondered what happened to it so if some knows please reply.

Hope this helps.

cp1969 · Jun 8, 2005

Diesel doesn't degrade at anything close to the rate that gasoline does, and gas is usually good for well over a year. I have hauled ten-year old diesel that, while it looked bad, was still good enough that the customer (a power utility) did not throw it away. It was standby fuel that did not get used, so they replaced it with new and sent the old stuff to another plant to be used immediately.

The reason it doesn't degrade is that the evaporation temperature of #2 is something like 140F, whereas gas is something like -70F. The lighter elements of gas evaporate away, leaving the heavier junk like varnish behind. Doesn't happen with diesel-there aren't any light elements to speak of.

My first car was an old Dodge that sat in a shed for ten years. It's gas had turned to asphalt in the tank--I had to cut a hole in the tank and scoop it out with a putty knife. I think gasoline has improved a bunch since then, though, as I have chain saws lawnmowers, tillers, etc., that might sit for a year or two with gas in them and have never had a problem. Knock on wood.

Lawnjocky · Jun 9, 2005

How long can I store diesel fuel?
If you keep it clean, cool and dry, diesel fuel can be stored 6 months to 1 year without significant quality degradation. Storage for longer periods can be accomplished through use of periodic filtrations and addition of fuel stabilizers and biocides.

That is a quote from the Exxon website FAQ section. You can do what you want but I'm staying with what works for me.