How much Sea Foam in a full tank of gas in a cargo van that has not been driven all winter? [SOLVED]

Thanks for the question!

If the tank is already full, I’d add 1–2 ounces of Sea Foam per gallon of fuel.

That said, the best cleaning results come from using a higher concentration. Here’s what I’d do:

• Drive it until the tank is down to about 1/4 tank or less
• Add a full 16 oz can (or even 2 cans)
• Drive it 10–20 miles (or until nearly empty) before refueling

Fuel that sits can form gum and varnish, which is the #1 cause of rough running after storage. Sea Foam works to liquefy and clear that out to help your engine maintain or recover strong performance.