I have heard of Seafoam but not sure what all it does and how to use it properly.

How long should I run it in the crankcase before changing the oil? Is it a good additive for the fuel system?

 

Yeah, I use both seafoam and mystery oil. Was introduced to seafoam when I first started dealing with marine engines. Though originally it seems that Johnson Evenrude was fond of, or had a stake in the company; I always used it on larger inboard equipment. Many times just to keep gas from going "sour" in the tanks of large Chriscraft- Chrysler equipped (or twin) systems. Worked great then and apparently it still does. I only worked on the Chrysler equipped models. I raced Chrysler products on the strip and worked on both marine and auto systems at the time.

Best way to understand this stuff is to read the bottle carefully. Yes it can be used in fuel, oil and even direct to the top of the intake by way of the PCV system. But dont take my word for it, check their site and read the bottle. All I can do is vouch for the fact that it has always seemed to worked for me, with no negative happenings.

I still like mystery oil for lots of applications, though again, I would suggest you read the instructions very carefully. It is very helpful in diesel applications and even does well with gasoline injection systems as well as crankcase work. Very helpfull in engine break in after rebuild or when building your own. I can only speak for diesel applications involving Mack engines of an out of date variety but have used it recently with success on modern automobile applications. This is really one to be careful with; a quart will take care of 100 gallons of gas. Dont just pour it in?