Wow, I can't believe it worked so well!

[shelby987]

This is just speculation, but I would assume you have a window of time during which the sea foam is still liquid and effective in softening the carbon build up. If you were to leave it in a warm engine for much more than 15 mins, I would assume that the sea foam would evaporate, and the carbon would re-solidify. I can't speak to possible negative side-effects of the extended time in the engine.

On a side note, shifty, I am pretty sure that once you put sea foam in your oil, you shouldn't drive the vehicle. When I do put it in my crankcase, I always do it after I have burned up all the sea foam/carbon I poured down the intake, then add the sea foam to the crakcase, idle for 5 mins, then change my oil, I don't think you should put much of a load on the engine with sea foam in the crankcase.