HOW TO USE MARINE PRO FUEL TREATMENT
IN BOAT ENGINE FUEL
BENEFITS
DIRECTIONS
treatment recommendations
SUMMARY
Add Marine PRO to every tank of fuel to help your marine engine start faster, run smoother, and last longer. It works through fuel injectors and carburetors to safely remove harmful engine residues and deposits from fuel passageways, intake valves, pistons and chamber areas.
Marine PRO is safe and effective in all 2- and 4-stroke gasoline marine engines, inboard and outboard. Marine PRO only contains petroleum-based cleaning and lubricating ingredients. It does NOT contain harsh chemicals or abrasive detergents that could harm your engine. Marine PRO does not contain alcohol.

HOW TO USE SEA FOAM
marine pro
RELATED QUESTIONS
Is it ok to use Sea Foam Marine Pro in my gasoline-engine car? I have carbureted and fuel injected vehicles.
Good question, Romeo. Yes, Marine PRO is safe and effective in a gasoline car/truck’s fuel tank. While it’s formulated for marine engines, you could use it in any gasoline engine. That said, if you have a choice between buying that or Sea Foam Motor Treatment (or High Mileage), go with Sea Foam Motor Treatment. If you have some Marine PRO you’re trying to use up, go for it!
How much Sea Foam can I put in my 5.0 Mercury boat engine?
Good question, Dan.
It’s safe to add a lot of Marine PRO to your boat’s gas tank. In fact, a high concentration of Marine PRO in fuel does a great job cleaning up fuel residues and deposits that often cause performance problems like rough idle, hard starts, and loss of power.
Here’s what I’d do: Wait until you have a low tank of fuel (1-2 gallons). Then, add a full can of Marine PRO to the fuel. Run your boat at least 20 minutes if you can (just don’t run out of gas!), and don’t be afraid to run it hard. After that, refill your fuel tank as normal and add 1 ounce of Marine PRO per gallon of fuel. That will prevent fuel from degrading and preserve ignition vapors.
In oil, add 1 ounce of Marine PRO per quart of oil.
I accidentally added Sea Foam Marine Pro to my diesel tank. Now I see on the label that it’s for gas. Put half a bottle into a 60 gal tank.
Thanks for the question, Kris. First off, there is nothing to worry about. Marine PRO is completely safe for a diesel engine. It’s not labeled for diesel engine use because the product was formulated for gas engines and the claims haven’t been tested in a diesel. That said, Marine PRO will still work to clean critical engine areas in your diesel. Go ahead and run it as normal.
In the future, you might be interested in Sea Foam Motor Treatment in the gallon container. You can find that at most auto parts stores.
How much Sea Foam should you add to a 10 gallon outboard fuel tank?
Thanks for the question, Brandon! Here’s what I’d recommend:
- For routine/preventative maintenance or storage: add 1 ounce of Sea Foam (or Sea Foam Marine PRO) per gallon of fuel in the tank.
- For occasional cleaning (once or twice a year): adding a high concentration of Sea Foam to your fuel will work the best to clean and overcome fuel-related performance issues. Here’s what I’d do: Wait until you have a low tank of fuel (1-2 gallons). Add a full 20 oz can of Marine PRO to the fuel. Run your boat at least 20 minutes if you can (just don’t run out of gas!), and don’t be afraid to run it hard. Then, refill your fuel tank as normal.
Here’s a (rather lengthy) explanation of why a high concentration works best. For upper engine cleaning (fuel injectors/carburetor circuits & chamber deposits that can affect running performance), it works much better to add the full can to a low amount of fuel for two reasons, 1) the cleaning concentration is considerably greater and, 2) the cleaning effect will start much faster with greater effectiveness. If you were to add Marine PRO to a high volume of tank fuel, it might take several hours of engine running for a lower concentration of the treatment to work its way through the fuel lines and through the engine. Understanding the concentration approach will go a long way in terms of understanding how Sea Foam’s engine products work for overcoming fuel residue restrictions or a rough-running engine. Pay attention to starting, smooth idle, throttle response, hole shot, acceleration, and top speed. The #1 cause of each of these issues is heavier suspended fuel gum and petroleum varnish that restricts fuel passageways. The most important thing Marine PRO does is liquefy and clear away sticky gum and varnish restrictions so the engine can go back to starting fast and running strong.
Hope that helps!
Can I soak valves in Sea Foam if they’re out of the engine?
Good question. Yes, soaking engine components or fuel system components (carb parts), transmission parts, and/or hydraulic system parts in a Sea Foam bath is a great way to clean parts.
Start with a slow cooker (crock pot). Either buy a new one for the kitchen (don’t use it for food again after using Sea Foam in it!), or purchase a cheap one dedicated to parts cleaning. Add enough Sea Foam Motor Treatment, High Mileage or Marine PRO to sufficiently cover the parts that need to be cleaned. Add the parts, put the cover on and turn the slow cooker on low or medium for 12-24 hours. After the “cooking time,” remove the parts and gently brush off the loosened contamination with a soft bristle brush or bottle brush to clean the remaining debris off the components. Pipe cleaners work great for small passageways. If there is still more contamination that needs to be cleaned, repeat the 12-24 hour “cooking time” and re-assess the parts. Hope that helps!
Jim D.TECH
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