NEW ON YOUTUBE: Toyota MR2 Built by F&F Legend

What Happens If I Didn’t Put Fuel Stabilizer in My Motorcycle?

Some snake oils aren’t worth skipping.

byHank O'Hop|
Cars 101 photo


We may earn revenue from the products available on this page and participate in affiliate programs. Learn more ›

Fuel! You forgot about dealing with the fuel before you parked your bike. Instead of getting ready to hop on the bike once the sun shows its face, you're in a panic over the nasty damage gas has done to your bike. Maybe you don't really care. It's only been a few months, and you believe fuel stabilizer is just another elixir manufactured by corporate bigwigs to get your money. Well, that's not exactly true.

Fuel stabilizer is a very important component in proper bike storage. Without it, there's a good chance that modern fuels are going to cause some problems for you. Problems that you need to deal with if you want that bike to run the way it was designed to. 

The Drive and its partners may earn a commission if you purchase a product through one of our links. Read more.

The sludge at the bottom is water that's separated from the fuel. Any time you take a sample, it's good to check the water content as well as the condition of the fuel. , Hank O'Hop

What Happens to Fuel When It Sits?

Ethanol gasoline is volatile and hygroscopic. As it sits, the fuel will naturally evaporate at the same time as water is absorbed. After so long, you'll wind up with a mixture that is less than optimal for burning. 

An interesting result of fuel sitting too long is that the octane rating will drop. If you can even get the bike to run with old fuel, it's likely that your engine will experience detonation and run poorly. 

That's not all, though. The evaporating gas will also leave behind varnish that's not going anywhere fast. This residue will collect throughout the fuel system, and you will need to deal with it in extreme cases. As if that's not bad enough, the water collected can cause corrosion on metallic parts. 

To make a long story short, you can use a stabilizer to eliminate or minimize these issues when you park the bike for any period of time. It’s also best to go out and start the bike from time to time to keep things moving. 

What Is Fuel Stabilizer?

Fuel stabilizer is and isn't a miracle product. In all reality, it's just a simple chemical mixture of lubricants and antioxidants that works to keep fuel from evaporating and absorbing water. Any time you store a bike, or any vehicle for that matter, you want to add a fuel stabilizer to help keep the gas from going stale.

For the most part, it does what it's supposed to, and bike owners lean on it because of its effectiveness. However, you really do need to be using good gas to start with to get the most out of it. 

And like anything, fuel stabilizers do have limitations. You can't expect them to work miracles. Some claim to work for up to 24 months, and you can trust that within reason. If however, the bike is stored outside or hasn't been kept up with properly, you may still need to run through the fuel system before that first ride anyway.

The fuel at far left is the freshest. Next to it is fuel that's been sitting for a few months. As you can see, it starts to fade to a dull, brownish color as it ages. , Hank O'Hop

How Long Can Fuel Sit?

Not all gas is the same. Some fuels can last several months before going bad while others will go stale within weeks. That’s why it's important to buy your gas from a reputable station. Even then, it's always better to err on the side of caution and put a stabilizer in whenever you plan to let the bike sit for a few weeks or more. 

On that note, just because you're paying for premium fuel at a crappy gas station does not mean you're buying fuel that's any better. There are no additional additives or miracle blends coming out of that nozzle. It's just fuel with a higher octane rating, which your bike might not need anyway. 

If you want to know more, you can read all about How Long Gas Lasts here. 

Will Treatments Reverse the Effects?

There are treatments that are designed to reverse the effects of time on gas. If it's only been a couple of weeks and the bike seems to run relatively well, you may be able to lean on them. Is that good enough for your standards? That depends. 

If the bike's been sitting for months and no stabilizer was added, your best bet is to get rid of it altogether. Drain the fuel system and add fresh gas to ensure there's no chance of stale fuel running through your system. 

In extreme cases, you're going to need to clean the entire fuel system. That fuel leaves behind a varnish that's all over the working parts by now. Fresh gas might clean it off, but there's really no promise of that.

Because fuels degrade at different rates and the condition of your bike as a result of it can vary, there's no definitive timeframe for a bike to sit in to warrant a thorough cleaning. Unless it's been a few years, just jump right into cleaning the entire fuel system. You can't rule out doing so even if it's been a few months because there's no telling what to expect. 

Anytime you drain the fuel, inspect the condition of the gas and take a look inside the tank to determine the best course of action. If the fuel is excessively cloudy and you can see varnish inside the tank, you know you have some work ahead of you. 

What Needs To Be Cleaned?

Cleaning the fuel system is a simple job, but you do need to be thorough. It's easy to just concern yourself with the tank, but that old fuel is looking to cause problems wherever it sits. So, deal with the tank, but don't leave out any of the other inner workings. 

In the case that you're dealing with an older bike, you need to run through the carburetor. Varnish and gunk can easily build up in the jets and many other small passages, which is sure to bog that bike down. The majority of you rocking fuel injection aren't getting off easy either. Both the injectors and pump should be cleaned out as well. 

As long as the fuel lines are in decent shape, you may be able to reuse them, but it's usually best to replace them. It's just one less thing to worry about, and that way you know there's no chance of gunk running through the system. While you're at it, you might as well replace any of the seals and o rings you encounter to make sure you won’t run into any leaks. 

FAQ on Motorcycle Fuel Stabilizer

You’ve got questions. The Drive has answers. 

Q. Can you mix new gas with old gas?

A. You can just add some fresh gas to the tank to revitalize old fuel. It's not your best option, though, because that old gas will bog down the quality of the fresh duel you're adding. It's better to simply drain the tank, dispose of the old gas, and run nothing but fresh fuel through the system. 

Q. How often should you start your motorcycle?

A. Once a week and let it run for 15 minutes. Doing so will ensure fuel is cycling through the system, keeping it from sitting and causing problems. Also, which is equally as important, it's going to keep seals and gaskets from sitting dry, which causes them to shrink and crack. 

Q. What is considered old gas?

A. Any gas that's been sitting around for 30 days is considered old. Now, you can argue with that if you're using high-quality fuel, but there's no room for taking chances on something you pick up from a shady gas station with suspiciously low fuel prices. 

Let’s Talk: Comment Below and Reach Out to the Guides & Gear Editors

We’re here to be expert guides in everything how-to related. Use us, compliment us, yell at us. Comment below, and let’s talk.  

Cars 101Motorcycles