i've read a lot about it being snake oil, I also read a lot about how other people noticed improvements on other forums, so I decided to draw my own conclusions.
last year I did the treatment on my dad's 90 toyota pickup (22-RE). My father is the original owner, it's been maintained very well and has 120,000km on it, no rust, looks like new! unfortunately it's spent most of it's life doing short trips, barely getting up to operating temperature. as a result, oil changes are very frequent, every 2-3 months, often with only 2000km on the oil fill. It burns no oil, but the fact that it's babied when driven and never gets very hot has led to some deposits in the intake.
The truck, despite frequent tuneups, had a slightly rough idle and was seriously down on power. it still worked great, but dad commented that "it didn't feel like this when I bought it".
The seafoam treatment did wonders for the truck. The cat continued to function and the 02 sensor did not foul. idle smoothed out and the engine was quieter when it was being driven. there was a large increase in low rpm torque, and a massive change in higher rpm power too. The transmission shifted less and power delivery was smoother. When rpm did increase, the engine sounded much smoother and quieter.
I swear, it worked. An independent tester (my mother) commented on the improvements, without telling her what we did, or to what component of the vehicle. it's certainly not a placebo.
perhaps water would do the same thing, I'm going to try that this summer, but I can't say anything but positive things about seafoam from my own personal experience. good to hear it helped you too!
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