Last night I did the seafoam, my truck has 151k. I put 8oz through the PCV line, 8oz in the crank, and another 8oz in 1/4 of a tank (I have 8oz remaining).
I yielded noticeable results. Smoother idle, smoother reving, way more pep which obviously translates to more torque, faster acceleration, and hopefully better gas mileage?
A side note, I notice people questioning what Seafoam "is", and how it works and everything. I took some Organic Chemistry classes in college and here is how Seafoam basically works:
First a background. In chemistry we should be familiar with the idea that "likes dissolve likes", meaning oils dissolve oils (because they're non-polar). There are 3 types of "likes" based on how polar a compound or chemical is: polar, semi-polar, and non-polar. This is why oil and water separate, because they don't mesh at all. Light oils float, heavy oils will sink (all depends on how dense the compound is) when mixed with water. Dissolving polar/semi-polar/non-polar compounds is why we use acetone to clean up some types of things and water for other things or oil for others. The closer the polarity of the solvent to the compound your dissolving, the better it will dissolve.
This is how Seafoam works. It is a petroleum (non-polar) compound that dissolves the specific non-polar compound that is carbon residue. This is important because the polarity carbon junk is different than octane, which is also different from oil lubricants, yet they are all close enough to be considered into the category of non-polar. So Seafoam should have polarity that very close to the carbon residue while far enough away from oils and octane to not break them down. To be honest it probably took a lot of engineering to make the solvent.
Last bit, things dissolve easier when you heat them up like water and sugar, or water and salt. This is why you have to warm up your car before you put in the Seafoam, the product would probably dissolve a bit, but not be as effective otherwise.
