Originally Posted by TheDude1982
It has been some time since I wrote the original article, but when I did I called the manufacturer of Seafoam and had a nice long conversation with him about what seafoam was and was not safe for. He swore up and down that seafoam will do no harm in your gas or oil tanks. I have put seafoam in the oil of my Honda civic and run it 3500 miles and had no problem. So I think it's safe, but I guess a matter of preference.
I don't know.There is a possibility that it took out an engine on another forum. Granted he put it in towards the end of his OCI and his oil was probably thinned out further than the 5w20 it started out as.
I would just rather be safe than sorry.
Here is a chemical breakdown of Seafoam vs Carb Cleaner