Build-up is good? News to me. Such breaking news, that I just cannot believe it without evidence.Engine build up in the internals is good, but you dont want alot. The build up help form tighter seals and protect the engine, pretty much like oil. Its always good to clean it up a lil to break down the build up, but using seafoam too much will clean it up too much and who knows what your seals ect might do.