2008-2013 Cadillac CTS Performance Mods Discussion, Another Catch Can Installation (with pics) in Cadillac CTS Second Generation Forum - 2008-2013; I'm quite familiar with Seafoam. But we have DirectInjection....
Seafoam, BG, and every dealer service center will have similar...does work, but some of those hard particles are forced between the piston and cylinder walls causing minor scouring, so it should be used spareingly. It is one of the easiest ways to clean the vlaves some (only manual cleaning will clean them like new again).
Refer to second half of post - you draw it in via vacuum port - works, just don't let it "drink" to fast.
OK, what port? The pictures are not of a DI 3.6. If I pull the engine cover off, there is the vacuum line coming from the PCV/Catch Can side. With this port removed, the engine will not start. And if you try to do this with the engine already started, you can't keep it running once you remove this line. so where is the preferred location to introduce the seafoam? Not everyone has an assistant on-call to assist with these things.
Ok buddy I hear ya, but with no cable driven throttle body, you are going to need someones foot on the gas. Use the vacuum side going to the top, center front of your intake.
I suggest using 3ft or so of clear 3/8" tube, and about 3ft of clear 1/8" tube - one that will slip INside the larger tube - overlap about 8" - this lets some air leak in around the two tubes and helps mix / regulate the flow of cleaner. Hold the small tube alongside the seafoam can and use a marker to indicate where about the top one third of the can is. Remember we use 1/3 the can only on a hot engine.
Use a tube clamp or vise grips to pinch the hose off so you can start your CTS
Carefully release the hose and meter the cleaner with the hose kink. You are being a sort of rudimentary carburetor! Your helper needs to increase rpm above idle as the engine labors on the cleaner some.
Shut it off and wait 15 min - fire it up and clean it out good with some mellow revs, then go drive it hard a couple runs.
I might try to make a video of this next week because I think this will come up again!