I recommend .5-1 ounce per gallon in a small engine. I know the can will say 2 oz----that is too much and WILL cause problems with any rubber or silicone.
In an automobile, to clean, and every 4 to six months, I recommend a pint can per 10 gallons and drive it till it is nearly empty. DO NOT keep topping off the tank. that does not mean you need to drive it to empty at one time, but going on a trip is ideal.
If you rarely drive an car, like an antique/show car, put in a pint can each time you fill the tank. USE EACH TANK before adding more fuel/Seafoam to eliminate rust and hard starts.
In all cases I have used these mixed fuels that were up to 3 years old with zero problems.
Deep Creep, the aerosol version of Seafom is outstanding as a gun cleaner, lubricant, rust buster, etc. Also you can spary it into the carb throat at high speeds on small engines to completely remove all carbon and varnish internally. Running it in the fuel will do the same thing only MUCH slower. Try it on a chainsaw and I'll bet you will have to retension the chain to prevent it from spinning after treting with spray----even a new engine. You can also fog for storage this way, except run it at idle and let the spray kill the engine. Your rings, injectors and valves will never stick or rust.
DO THIS ONLY OUTDOORS!!!!!!!!
To do a large, automotive type, get a hose to attach to the PCV port on the plenum/manifold (usually 3/8"). If you can control the throttle by hand, great, if not, you'll need to get someone to control the foot pedal. If the hose will fit loosely into the can, use it. If not pour all the Seafoam into a tall jar. Start the engine, you may need to give it a little throttle to keep it running and the check engine light may come on because the PCV hose is disconnected. Once the engine is running, stick the hose all the way to the bottom of the can or jar, at the same time QUICKLY rev the engine to an immediate FULL throttle and let then let the throttle slam shut to create maximum vacuum. This should happen in about 5-7 seconds and if it was done properly, nearly all the Seafoam will be gone and it should have killed the engine. TURN OFF THE IGNITION!!!!! DO NOT RECONNECT THE PCV HOSE YET!!
Go drink your favorite beverage and wait about 10-30 minutes. Hold the gas pedal to the floor, (to shut off the injectors or to air out the flooded condition on a carb model), and crank until it starts (10-15 seconds). Keep the pedal to the floor until the engine begins to rev higher and run smoothly. THERE WILL BE LOTS AND LOTS OF SMOKE----THIS IS NORMAL!!! Keep the engine running for about two minutes with the PCV hose disconnected and then reconnect the hose (to clear liquid Seafoam from any rubber hoses). Go out for about a 15 minute drive and rapidly accelerate often. Be prepared to have people cuss you because it will look like you are on fire for a few minutes as the Seafoam gets burned out of the exhaust pipes.
You can also add seafoam to crankcase oil and drive about 100 miles before changing your oil to clean and dissolve the sludge that builds up.
Seafoam has several oil based aromatic solvents and Ionized lubricants that burn at high temps. It also includes OIL based Isoprpyl alcohol to remove water and moisture. The solvents will all evaporate and the lubricants are very low viscosity and remain in a system due to their magnetic nature.
