That sounds like pretty simple instructions "pour in gas tank". Why would they leave the best parts out?

 

Having worked in and around the automotive industry for nearly forty years now, and I've seen miracle elixirs come and go, and so far at least, the only one which has garnered any industry respect is Techron, a formulation which has proven so effective, virtually every gasoline producer in North America now uses a variation of the Techron formula in their gasoline. Seafoam, Slick50, Motor Honey, you choose, as a general rule, such formulations are considered to be huile de serpent by the industry professionals. Spend your money if it makes you feel better, but please know, any claims of efficacy will be looked upon with a serious degree of skepticism by anyone in the industry (save those who actually sell such products).

 

Seafoam was developed during WW II for the US Navy to help clean their boat engines. The Navy discovered their engines worked better after use, so I doubt it is a "snake oil"product, but it is over-priced.

I bought a used motorcycle that ran rich when I first got it and therefore, had a lot of carbon buildup in the engine causing high compression beyond recommended levels. I used the Seafoam in the gas and in the oil. The oil I changed after a very short ride. It cleaned out the carbon and compression returned to normal levels. In the gas, it cleaned out the carbs and the bike ran much better. Snake oil or not, the results was enough proof for me. I don't know anything about its utility in modern engines, but I use it maybe once every year or two in the gas tank and I think the car runs better afterwards. Just my two-cents worth.

 

I won't use Seafoam or any system super cleaners for one reason. I drive older cars in the Northeast US. Why? because sometimes it's the gunk that holds everything together and old gaskets and O rings don't need "Extra" cleaning, they would likely develop a leak.

 

Completely true, I've read about that. Sometimes it's better to leave it as it is for older cars. My car is 5 years old so I wouldn't mind keeping everything as clean as possible.

What I've read is that to do a 'thorough' Seafoam cleaning you basically use the cleaner in 3 places: your oil, your gas tank, and through the brake booster/PCV line. Not quite sure how to do the last part so for now I'll just skip it.