Can I use Sea Foam in full synthetic oil? [SOLVED]

Good question, Kenneth. First off, yes, Sea Foam Motor Treatment is safe and effective in full synthetic oil. Add 1 ounce of Sea Foam per quart of oil in the crankcase.

Second, we always recommend draining “bad gas” if possible. Sea Foam won’t “change” bad gas or make the gas better, but it will clean gum and varnish that often forms due to old fuel. Add two cans of Sea Foam High Mileage to a low tank of fuel (1/8 tank or so) and run until almost empty before refueling. That will do a great job cleaning up the fuel system after having old fuel in it.