Bad gasoline can gum up fuel system components, damage the engine and degrade performance.So it’s important to either go boating enough to keep burning through the gasoline you have in the fuel tank before it goes bad, or take measures to make sure you’re not left with a batch of bad fuel. The longest you will ever need to plug in your diesel engine is four hours. After that, you will only waste electricity. However, you can keep an eye on the outside temperature to determine whether to keep it plugged in longer or to unplug it earlier. Do not plug in your engine overnight. Diesel engine tech here, 600 gallons of diesel, just use a anti microbial additive to it, and in colder months ether have it drained all the way, or full as much as you can. Water and microbes are the biggest killer of diesel. And every other year, drain the tank and scrub it down. A good example of a diesel microbial growth remover is CleanBoost® Anti-Microbe Fuel Conditioner. This product can be used in both diesel and bio-diesel fuels and is best added during the refilling of fresh fuel to the tank. It is capable of killing even the organisms that are hardest to remove in just a few hours. How Long Does Diesel Last In A Tank: Factors, Testing, Storage, And Signs Andrew Nelson Andrew A. Nelson is a fuel enthusiast and writer with a passion for exploring the science and technology behind the fuels that power our world. How Long Does Diesel Fuel Last? Under optimal conditions and assuming the quality of the fuel is high, you can expect it to last for up to one year or more. At higher temperatures (86 degrees Fahrenheit and above), this estimate decreases. In this instance, storage life expectancy is six months to a year. For example, fuel tank full; winter additive added, is it recommended to start and run either the coach engine or the onboard deisel generator during the 3-4 monthsif yes for how long, etc. Looking for solid technical advice more so than opinions How Long Does Diesel Last? The shelf life of diesel fuel can vary depending on several factors such as the type of diesel, storage conditions, and the presence of additives. Generally, diesel fuel can last between 6 to 12 months without significant degradation if stored properly. Common Emergency Fuels and Their Shelf Life. Store in 5-gallon blue containers away from direct sunlight. Store in red gas cans in a cool, dark, and ventilated area. Store in yellow gas cans in a cool, dark, and ventilated area. Store in 1-pound to 30-pound tanks outside in a cool area. Keep in airtight containers. 1. Heating Oil Storage. Heating oil can be stored in your tank for up to two years without problems. In fact, it can last for 10 years if stored in ideal conditions. Heating oil is more stable compared to gasoline and other kinds of fuel, meaning it doesn’t break down easily. DkysK1.