Can I add Sea Foam when there is another additive in the tank? [SOLVED]

I put a different brand in when my tank was half full and filled up the tank. I was not impressed with the results. Is it okay to put Sea Foam Motor Treatment in the fuel with the other additive now that I am at half a tank again, or should I wait till the rest of the other stuff goes through after a couple more fill ups?

The engine is a GM 4.2 I6.

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Jim D.
2 years ago

Hi Don,

Yes, it is okay to add Sea Foam to your fuel tank with another additive in it. Mixing them will not hurt anything. Here’s what I’d do: wait until you are at a quarter tank or less, and add a full can of Sea Foam Motor Treatment. Drive at least 20 miles before filling your tank to let the Sea Foam work through the system. Using a higher concentration of Sea Foam like that will do a great job cleaning out the engine – it’s one of the best ways you can use it! Hope that helps!

Mohammadali Izadi
Mohammadali Izadi
1 year ago

Is it possible to put Sea Foam Motor Treatment in both the engine oil and the gas tank at the same time?

Dallas Harris
Dallas Harris
5 months ago

I have a 99 F350 7.3 Diesel. Question is: Do you have to run the engine out of the first additive, specifically Motorcraft Cetane Booster, before adding Sea Foam? I put the Cetane in and haven’t ran the truck yet. I have been now that told Sea Foam best to use after I had used the Cetane Booster from Ford.