Originally Posted by B7Night

Only if you can get the seafoam in the intake upstream of the valves. Remember with a DI engine, the fuel injectors are in the cylinder, and not upstream of the intake valves. So any Seafoam put into the gas tank will not have any effect on the intake valves, only the cylinder walls and exaust valves. The intake valves are closed when the fuel is injected, keeping any fuel/detergent mixture from coming in contact with the crudy upstream side of the intake valves.

Originally Posted by Progress

From my experience, most people apply Seafoam by way of the air intake such as a brake booster hose. That's what I have done as well.