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Does Gasoline Go Bad in Your RV & Generator?

Does gasoline go bad? If your RV or generator runs on gasoline, you need to know the answer to this question. Especially since the answer might surprise you…

Do you drive an RV that runs off gasoline? Do you use a gas generator? If so, you might be surprised at how quickly gas goes bad. Because it does, in fact, go bad.

The shelf life of your gas depends on a few factors, and there is a way to extend it.

So, I’m going to tell you what you need to know, from why gas goes bad to how you can make gas last longer. Even if your RV runs on diesel, you should keep reading as some of the tips apply to diesel as well.

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Does Gasoline Go Bad… Really?

Does Gasoline Go Bad in Your RV & Generator?

Yes, gasoline does go bad. It doesn’t have a set expiration date, but it does degrade over time. Unfortunately, gasoline’s shelf life is shorter than most people think.

Gasoline is a mixture of volatile compounds that don’t just patiently sit there, waiting to be used. Over time, the compounds degrade and evaporate and thus affect the quality of the gasoline. The gas starts to become gummy, which in turn affects how well your engine runs.

Is It Okay to Use Old Gas?

It’s not a good idea to run your RV or generator on old gas. While old gas might get you down the road, it can cause damage to your fuel system and engine.

At best, old gasoline decreases your RV’s overall performance, decreasing your fuel economy. Simply put, fresh fuel means better fuel efficiency in your RV; bad gas means bad gas mileage.

At worst, however, bad gas can cause serious engine problems. This includes engine knocking, sputtering, and clogged injectors. As gasoline degrades and becomes gummier, it can clog filters, gum up the fuel lines, and damage the fuel pump and several other engine components.

How to Get Better Gas Mileage in Your RV

How Quickly Does Gas Go Bad?

The shelf life of gasoline depends on a few factors. However, in general, gasoline goes bad in 3-6 months. This timeline isn’t a problem when you camp regularly. However, if you store your RV during the off-season or for prolonged periods of time, then old gasoline can become a problem.

Don’t worry, I’m going to tell you how to maximize the shelf life of your gasoline. There are a few sure-fire tricks that will make it last significantly longer. But first, I need to quickly explain what causes gas to go bad.

(By the way, Diesel fuel can last up to a year before it starts to degrade. It can start to degrade as early as 6 months if it’s not stored properly. But, in general, it’s good for 12 months. Then, it starts to degrade, much like gasoline does.)

Does Gasoline Go Bad in Your RV & Generator? 1
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What Causes Gas to Go Bad?

The three main culprits that make gas go bad are water, evaporation, and oxidation. The amount of time your gas lasts depends on how active these culprits are. Let me explain…

Water

Water molecules interact with ethanol, which shortens how long gasoline lasts. The more ethanol content in fresh gasoline, the more quickly water vapor will degrade the gasoline.

In the United States, almost all gasoline is blended with 10% ethanol, which is one of the main determining factors of the 3-6 month shelf life.

Evaporation

Gasoline is also highly evaporative. You may remember from a very helpful RV Lifestyle Facebook post that you shouldn’t let your gas tank get low because gas will evaporate faster. The longer gas is exposed to air in your RV or car’s tank, the more will evaporate.

Fuel producers even account for how gas evaporates at different temperatures…

Did you know that gasoline has different gasoline blends in the winter and summer? Winter blends have a higher RVP (Reid Vapor Pressure) and evaporate more easily, so you can start your RV or generator in cold temperatures.

Since winter gas is not as dense, so to speak, it’s cheaper to produce. That’s why gas prices at the gas station are typically lower from late September through late April.

Does Gasoline Go Bad in Your RV & Generator?

Oxidation

Evaporation leads to oxidation, which means oxygen reacts with hydrocarbons in the gasoline. These unwanted chemical reactions cause the gasoline to solidify and “gum up.”

How Can You Tell If Gas Is Bad?

The best way to tell if gas has gone bad is by its smell and color. Of course, you don’t want to go around sniffing gasoline all day. But, a quick sniff can alert you to bad gasoline if it has a sour smell.

Some people describe this sour odor of stale gas as smelling more like varnish than gasoline. You’re likely more familiar with the smell of regular gas than you think. So, if it doesn’t smell right, it probably isn’t.

Another easy way to tell if gas is bad is by its color. Old fuel is darker than fresh fuel and, as we explained, is gummier.

How To Make Gas Last Longer

Thankfully, there are a few great tricks to make your gas last longer. Keep in mind, if you’re going to go through a tank of gas within a couple of months, you don’t really need to concern yourself with these tasks. But if your RV or generator is going to sit for an extended period, you should definitely employ them.

Use a Fuel Stabilizer

Does Gasoline Go Bad in Your RV & Generator?

The first and most effective way to make gas last longer is to use a fuel stabilizer. A popular option is STA-BIL Fuel Stabilizer, which keeps fuel fresh for up to 24 months! That’s 4 times as long as untreated gasoline!

It works in all ethanol-blended gas. The one I linked to is specially designed for storage. So, you can add it to your to-do list when winterizing your RV.

It’s best to pour the recommended amount of fuel stabilizer into your tank before you fill up. That way, it gets properly mixed with the gas. Then, run the engine for at least five minutes to treat the entire fuel system.

Refill Your Gas At Half a Tank

paying for gas - Does Gasoline Go Bad in Your RV & Generator?

Remember, one of the biggest components of gas degradation is evaporation. The more air in your gas tank, the more quickly it will go bad. So, the best solution to combat evaporation is to refill more often.

Many people suggest you refill at half a tank. This will optimize fuel efficiency and help extend the previously-filled gasoline’s shelf life.

This also means it’s better to store your RV tank full than half empty, especially in conjunction with a fuel stabilizer.

Store in Optimal Conditions

If you have to store gasoline, then you want to store it in as optimal conditions as possible. This means storing gasoline in an airtight container in a cool, low-humidity, low-oxygen environment.

Don’t Give It a Chance To Go Bad

Another way to keep your gasoline from going bad is to drive more! This isn’t the most budget-friendly advice, but it is the most fun solution!

After all, if you RV more, your gas won’t have a chance to go bad. I have a whole library of RV travel guides to keep you on the road. Plus, you can use the following apps to keep you on the road for less…

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RV Lifestyle recommends the RV Tech Course

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