AMSOIL vs. Sea Foam

Which product will provide the most protection for stored engines, AMSOIL Gasoline Stabilizer or Sea Foam Motor Treatment?

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Brad Nelson
by Brad Nelson
August 15, 2025

The simple act of storing seasonal equipment can wreak havoc on an engine, leading to lost time and expensive repairs, not to mention a solid dose of frustration. Why? Because gasoline begins to break down in as few as 30 days. Varnish and gum begin to form, clogging tiny fuel passages inside the carburetor or injectors. In addition, components of the fuel system can corrode and not function properly. For these reasons, when storing seasonal equipment, like a snowblower in the spring or lawn mower in the fall, using a fuel stabilizer is essential. But what product will provide the most reliable protection for stored engines, AMSOIL Gasoline Stabilizer or Sea Foam* Motor Treatment?

Stored seasonal equipment sit in a shed.

How the Two Compare

As the graph below shows, AMSOIL Gasoline Stabilizer delivers 8X longer fuel stability than Sea Foam Motor Treatment in the triple-length gasoline oxidation stability test (ASTM D525), helping maintain startability and protect against the formation of varnish and gum.

AMSOIL Gasoline Stabilizer delivers 8X longer fuel stability than Sea Foam in the triple-length gasoline oxidation stability test (ASTM D525), helping maintain startability and protect against the formation of varnish and gum.

Our stabilizer keeps fuel from deteriorating for up to 12 months, allowing easier startups. It resists the formation of varnish and gum to keep fuel systems and storage tanks clean. It’s effective in ethanol-blended fuel and ideal for all two- and four-stroke engines, including motorcycles, snowmobiles, boats, ATVs, edgers, tillers, mowers, cars, trucks, snowblowers, chainsaws, generators and farm and construction equipment.

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AMSOIL provides corrosion protection that far exceeds Sea Foam Motor Treatment, helping maintain power and performance and keeping metal looking like new, even when subjected to salt water.  Check out the image below to see the difference between AMSOIL and Sea Foam in a head-to-head corrosion-protection test.

AMSOIL provides corrosion protection Sea Foam* Motor Treatment can’t match, helping maintain power and performance and keeping metal corrosion free, even when subjected to salt water.

AMSOIL Gasoline Stabilizer can save you time and money. It helps reduce downtime and maintenance costs by preventing harmful deposits from forming in the tank and fuel system and eliminating the need to clean or replace carburetors after long-term storage.

Video transcript: How to Get your Lawnmower Ready for Storage

Welcome to Tech Tips. I’m Len Groom, Technical Product Manager for Powersports. A lot of people ask me, What do I need to do to put my lawnmower in storage? Well, here’s a few tips that will help to ensure that your lawnmower will start up when you get it out of the shed in the spring.

The first and probably the most important thing to do would be to change the oil. Contaminants can build up from combustion, from use, from dust and dirt in the environment, and they can end up in the oil. So it’s always good to put the mower in storage with fresh oil in it. Changing the oil isn’t that tough.

Here’s how you do it. The first thing you need to do is drain the oil out. So you want to locate the plug which is underneath, remove it and drain the oil into a pan. You want to add the appropriate amount of oil until the dipstick registers full.

I recommend AMSOIL’s Formula 4-Stroke Small Engine Oil in 10W-30 for this application. Next, you want to treat the fuel. No matter what type of fuel you’re using, you always want to treat it. AMSOIL has two different options.

The first one would be AMSOIL’s Gasoline Stabilizer. This one is designed for long-term storage. This will help fight all forms of fuel deterioration from corrosion to varnish to any type of buildup. This is for long-term.

The second option would be AMSOIL’s Quickshot. This is designed to be used over the course of the summer. This will also help fight corrosion. It will help fight any type deterioration.

But this product also helps with any of the issues that are associated with ethanol. So, one way or the other, make sure you’re treating your fuel. Next, let’s take a look at the air filter. It’s often overlooked.

It’s usually pretty easy to get to. So you want to take the cover off, inspect it, clean it if you can. But, if it’s too dirty, replace it. So there you have it.

Just a few simple things that you can do to ensure that your mower comes out of storage ready to run. One thing we should note: If you ever have a question on quantity or any of these procedures, the first thing you should do is consult your owner’s manual. One last thing: Some of these new lawnmowers, specifically the push mowers, don’t have a drain plug. So you need to look in your owner’s manual for the procedure.

Most of the time it’s going to want you to drain the oil out through the filler neck. Thanks for watching. We’ll see you next time.

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by Brad Nelson

Brad Nelson is an AMSOIL Technical Writer II who develops content about lubricant technology, product performance and vehicle maintenance. He works with engineers and product specialists to translate testing, application requirements and approved performance claims into clear customer guidance. Nelson’s work includes AMSOIL Blog articles, AMSOIL Magazine features and technical explanations concerning motor oils, gear lubricants, vehicle systems and maintenance practices.

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