Thanks for the question, Braden!

Sea Foam can be added to one-year-old gasoline, but it cannot restore fuel that has already degraded.

If the fuel still appears to be in good condition, Sea Foam can help stabilize it against further degradation and dissolve any gum and varnish that may have started to form. However, with fuel that’s already a year old, fresh gasoline is the safest choice, especially for a generator that you need to be reliable.

For future storage, add at least 1 ounce of Sea Foam per gallon of fresh fuel before storing, and run the generator long enough to draw the treated fuel throughout the fuel system. Sea Foam will help stabilize stored fuel for up to two years.

Thanks for the question! Yes, you can use Sea Foam Motor Treatment in any gasoline or diesel fuel, including ethanol free gasoline. Just follow the directions on the can.

Hi Harry ,

Thanks for the question! Yes, you can use Sea Foam in a Stihl chainsaw, and any other gas or diesel engine.

For preventative maintenance, add 1 ounce of Sea Foam per gallon of fuel to every tank. That will keep fuel from degrading and prevent gum and varnish from forming. For cleaning the entire fuel system, use a high concentration of Sea Foam – up to a 1:2 ratio of Sea Foam to gas. If you’re experiencing problems with it (or want to just do a really good cleaning), I’d add 4 oz of Sea Foam to 8 oz of gasoline and run it for about ten minutes, shut it off, let it sit overnight, and then run it for a few minutes again the next day. That will do a great job cleaning up any fuel gum or varnish that’s formed anywhere in the fuel system. Gum and varnish is a very common cause of problems in a small engine like that.

Thanks for the question, Don.

For your 2023 Street Glide with a 6 gallon tank, here are a few good guidelines:

For regular preventative maintenance:

Add 1 ounce of Sea Foam per gallon of fuel (so about 6 ounces for a full tank).
That will help keep the fuel system clean and prevent gum and varnish from forming.

For cleaning (best way to get the most out of a can of Sea Foam):

The best way to get the most cleaning power is to use a higher concentration. Here’s what I’d do:

• Wait until the tank is low (1–2 gallons)
• Add a full 16 oz can of Sea Foam
• Ride it for at least 10–20 miles before refueling

That gives the treated fuel time to work through the system. The higher concentration works much better and faster to clean fuel residues and deposits.

For storage:

Add at least 1 ounce per gallon before storing the bike. Sea Foam will help stabilize the fuel and prevent gum and varnish from forming while it sits.

You don’t have to be exact with measurements. Sea Foam is petroleum-based and okay to use in higher concentrations.

Hi Dennis,

Thanks for the question!

Best practice would be to drain the fuel.

After one year though, it should still start and run fine. If you don’t drain it, I’d wait until you have 2-4 gallons, add an entire can of Marine PRO, and run it for at least 20 minutes (just don’t run out of fuel). The high concentration will do a good job cleaning up any gum and varnish that formed while the fuel sat. After that, add 1 ounce of Marine PRO per gallon to every tank of fuel. That will prevent gum and varnish from forming going forward.