Thanks for the question! It is absolutely okay to add it to a tank of fuel and let it sit for a while. It’s made with 100% safe petroleum cleaning and lubricating ingredients that can’t harm parts or components. The Sea Foam will actually help prevent fuel from degrading while it sits, so it’s a good thing to have in the fuel tank of a car that doesn’t get driven often.

I would add it before you drive, though (rather than after you park it). That allows the treated fuel to run through the fuel system. If you add it after you park, the untreated fuel in the fuel lines won’t be protected from degrading.

That said, here’s how I like to use it for cleaning: wait until the tank is low (1/4 -1/8 tank), add the whole 16 oz can, and then drive for at least 10-20 miles before refueling your tank. The high concentration works very well for cleaning fuel residues and deposits. It works better and faster than adding a can to a full tank of fuel.

If you’re going to park your car for a while like you mentioned, you could add 1 oz of Sea Foam to the tank to protect the fuel.

Thanks for the question, Vern. Sea Foam Motor Treatment is made with 100% safe petroleum cleaning and lubricating ingredients. You can safely add a large amount of Sea Foam to your gas tank – there’s no such thing as “too much.” In fact, a high concentration of Sea Foam in the fuel tank works better and faster to clean than a low concentration. I like to wait until the tank is low (1/4 -1/8 tank), add the whole 16 oz can, and then drive for at least 10-20 miles before refueling. It’s safe to add a high concentration like that and it works very well for cleaning fuel residues and deposits.

In the oil, do not exceed 1 ounce of Sea Foam per quart of oil.

Good question, Tyler.

For Sea Foam in the gas tank, yes, you can use the whole can. Adding a whole can to the gas tank is a great way to clean up the entire fuel system. I like to wait until the tank is low (1/4 -1/8 tank), add the whole 16 oz can, and then drive for at least 10-20 miles before refueling. It’s safe to add a high concentration like that and it works very well for cleaning fuel residues and deposits.

In the oil, add 1 oz of Sea Foam per quart of oil. Do not exceed that ratio.

Thanks for the question, Blaine! Here’s an overview. It depends why you’re using it:

• For preventative maintenance/fuel storage: 1 oz per gallon
• For fuel system cleaning/overcoming a fuel-related engine problem: 2 or more ounces per gallon. To maximize cleaning, add a full can (16 oz) to a low tank (2-3 gallons) and drive until almost empty before refueling.