Hey I used seafoam in my brake vacuum line about 1/3 the can poured in slowly until it died. I waited 15 minutes then told my son to come outside so he could see the "smoke show" only to start it up and what happened
..... not a drop of smoke!! I guess thats a good thing and must be pretty clean inside the engine. My kid said "Yeah thats great Dad"
and walked back inside. Nice.