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.

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!

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!

Good question. If your Mercury is running poorly, add a full can. If it’s running fine, you can add the 1.5 ounces per gallon as preventative maintenance to keep things running clean and prevent the fuel from degrading.

Thanks for the question, Christine!

Yes, you can still add Sea Foam. It will still stabilize and protect the fuel in the fuel tank. Add a minimum of 1 oz per gallon of fuel in the tank. Adding a whole can works too if you want to go the simple route. Adding more than 1 oz per gallon is fine and will do a good job cleaning up any fuel residues when you run it in the spring.