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.

Good question, Rob.

Thanks for the question!

It depends on what you’re trying to do. Here are a few good guidelines for small engines like a lawn mower or weed eater:

For regular use/preventative maintenance:

• Add 2 ounces of Sea Foam per gallon of fuel.
  This helps keep the carburetor and fuel system clean and prevents gum and varnish from forming.

For cleaning (which is one of the best ways to use a can of Sea Foam):

Use a higher concentration. Here’s what I’d do:

• Add a strong mix (up to about a 1:2 ratio of Sea Foam to fuel)
• Run the engine for a few minutes to pull the treated fuel into the carburetor
• Shut it off and let it sit overnigh
• Run it again the next day

The high concentration works better and faster to clean out varnish, which is the #1 cause of rough running in small engines.

For storage:

• Add 2 ounces per gallon before storing.
  This helps stabilize the fuel and prevents gum and varnish from forming while it sits.

No need to be exact with measurements. Sea Foam is petroleum-based and safe to use in higher concentrations.

Good question, Olivier. You’ll want to add a strong cleaning concentration to take care of any fuel gum and varnish in that has formed while it’s sitting.

Here’s what I’d recommend:

• Drain any old fuel completely
• Add fresh fuel mixed with a strong cleaning concentration of Sea Foam (up to about a 2:1 ratio of gas to Sea Foam for cleaning. 8 oz of gas and 4 oz of Sea Foam is a good amount for a scooter).
• Start and run the engine as best you can to draw the treated fuel into the carburetor. Let it idle for a few minutes.
• Let it soak overnight (or longer)
• Then start it up and take it for a ride. The Sea Foam will continue to clean as it burns through the treated fuel. Once it’s running and smoothed out, add fresh fuel. You can add 1 oz of Sea Foam per gallon of fuel in every tank if you like. That’ll help prevent gum and varnish from forming and keep it running strong.

Hope that helps and let me know if you have any other questions!