Adding Sea Foam to old gasoline [SOLVED]

Hello there! My issue is that I am a cottage caretaker and have several clients whose vehicles have now been sitting for nearly two years with most having full tanks of fuel . I’ve never used Sea Foam before after just hearing about the product from a friend and am anxious to try it . My question is will the Sea Foam help with this old fuel when added to prevent the fuel from worsening? I really don’t want to try and drain all of these fuel tanks.

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Jim D.
2 years ago

Great question, Ruck. There are two things about Sea Foam that likely caused your interest: 1) Sea Foam helps to stabilize fuel/prevent fuel from degrading over time, and 2) works in the fuel system to clean suspended gums/varnish that can impair engine performance. Here’s my take: If the tank fuel is two years old the vehicles should start and run fine. Additionally, adding Sea Foam to gasoline that has already degraded a bit, mainly the evaporation of light ignition vapor, won’t restore the fuel back to normal. [You need to siphon or burn through the current fuel, not postpone while the fuel gets worse/degrades more.] What I would do is run or siphon each vehicle until the fuel is a quarter tank or less, then add a can or two of Sea Foam to the tank and continue to drive – this will allow the higher cleaning concentration to clean the heavier gum/varnish from the fuel passageways. Once you’ve drive at least 20 KMs, can add a partial tank of fresh fuel. By the way, you can re-use the siphoned fuel in a car or truck if mixed with fresh gas. Hope this helps!