The Mopar combustion chamber cleaner PN 04318001AB is far better than Seafoam. I have used both and the Mopar just works very well. It's about $7 a can from your dealer. I use it sucked into the carburetor or throttle body through a vacuum port and directly into the plug holes, after which you should change the oil. There are directions for both methods.
I have never dumped Seafoam into my oil though. I know back a few years ago they used to have a motor flush for slugged up motors and it was basically kerosene. You had to change the oil after running it through a couple full heat up and cool down cycles and it did pull some dirt and sludge out of the motor but thinning the oil like that just does not seem like a good thing but some times it is needed.

I'm a Seafoam fan.... I put in my cars to keep the fuel fresh because they hardly get driven but when I drive them they get driven "hardly" . The car I'm building now sat in a field for 15 years and must have had a full tank of fuel. The fuel turned into something that resembled tar. The tank was trash but I wanted to save the fuel lines that were also filled with the tar stuff. I tried to blow it out with compressed air but it wouldn't move. I capped off the low end of the fuel line and filled it with seafoam. The next day the tar ran out like water. So it does a good job of cleaning. I put it in the vehicles I drive all the time about every 5,000 miles to clean the fuel system and so far so good. Just my opinion.

As for mixing into the oil - get good results cleaning the internal engine with a quart of atf in the oil for the last 5o miles before a oil change. ATF is high in detergency. Also works on dirty hands as well as gojo.

I've used it for fuel stabilizer/moisture for many years, started with boats. For carbon, I just use water down the carb & for gummed up engines I use kerosene but, do not drive it/leave it in.