The problem I see with seafoam is once all the sludge build up starts to brake up.... Well you can imagine....

So, the way I see it, seafoam is great for a newer car with little miles that gets an oil change every 3k miles or less, and gets driven everyday.

I use a penzoil oil that cleans the engine in a milder fashion every 6 months, I run it for 1000 miles and change it back to motorcraft. The penzoil is very clear( looks like cooking oil).

I'm very picky in what goes into my engine, and often refer to most things like this as crap in a can.

IMO....