Stored diesel fuel needs a stability treatment added to it if the fuel’s quality is to be retained for a longer period of time.
Stored fuel is subject to the effects of oxygen, water, and catalytic metals that it might be exposed to over its life. Any of these elements will trigger chemical chain reactions in the fuel, ultimately leading to polymerization and heavy end fallout in the fuel.
That’s what is happening when you see old fuel change color and stratify. Formerly-soluble portions of the diesel fuel have become unstable and insoluble because of these chemical reactions. Darkened fuel and the formation of sludge, gums and varnishes are typically the result. And that's bad news for any engine trying to run on that bad fuel.
Adding a fuel stabilizer before this happens is the best way to protect the stored fuel’s quality. You add the stabilizer when the fuel is fresh, and the chain reactions never get off the ground.
Given the large number of choices out there for someone considering a diesel fuel stabilizer, most people have no idea what they should be looking for or if there’s any difference in their choices. The chemistry behind stabilizers can be technical. So here’s a couple important tips on what to look for in picking the right one for you.
Make sure it covers all your needs
Stabilizer additives are rarely just one thing. The best stabilizers are packages with multiple ingredients, because they need to address the biggest causes of fuel instability
- ANTI-OXIDANTS to stop oxidation reactions in the fuel (reactions stemming from the fuel’s exposure to oxygen).
- DISPERSANTS to take newly formed sludge “particles” and keep them from sticking together and forming larger particles. This is important because if those particles get dark enough, that when they come out of solution and start sticking to things.
- METAL DEACTIVATORS react with all soluble metals in the fuel to prevent them from causing chain reactions.
You definitely should look for a stabilizer that talks about containing all of these kind of ingredients. Such a stabilizer is going to be the most effective for what you need it to do.
Economical treat rate
Protecting fuel stability in storage is definitely a valuable thing to do when you calculate out the monetary value of the fuel itself. But there are enough options in the marketplace that it should not be terribly expensive to use a good quality stabilizer.
The economics of treatment are most influenced by the treat rate. The lower the treat rate, the less it’s going to cost you to get the job done. Remember that low treat rate, in this context, means higher number of gallons treated per gallon of stabilizer. The lower the treat rate, the more fuel it treats. That’s good. The higher the treat rate, the LESS fuel it treats. That’s bad.
Lower treat rate (more fuel treated) = GOOD.
Higher treat rate (less fuel treated) = BAD.
There’s no reason to use a stabilizer with a treat rate higher than 1:2000. This means each gallon of stabilizer should treat a minimum of 2,000 gallons of fuel. Preferably more.
Make sure you cover those two areas, and you should be able to protect your stored fuel effectively with a minimum of cost per gallon.
Read more about diesel fuel:
- Diesel Fuel Additives: Top 5 Things You Never Knew You Didn't Know
- Diesel Lubricity Additives - Solving Your Diesel Fuel Problems
- Guidelines For Long Term Fuel Storage of Diesel and Storage Tanks
This post was published on April 14, 2015 and was updated on October 20, 2020.