2000 Cadillac Deville SEAFOAM VS GM TOP ENGINE CLEAN

From a dealer, and been using GM T.E.C. Have not used the seafoam, nor know the method it is delivered. Typically, I meter it through the vacuum system with the throttle raised, on a warm engine, until it bogs or dies. Allow it to sit for several hours, start it up, and throttle it until the smoke diminishes. Often times used for carbon knock, or used as preliminary in addressing excessive oil consumption.

Safe as in 'will it deteriorate rubber?'. I have had no problem with it. I usually connect a clear hose to a vaccum port, and use pinch off pliers, or a clamp to meter it's delivery, and avoid a potential for slugging or hydrolock.