The conventional wisdom on this site is that the vacuum suck IM cleaning method is best for maintenance cleanings every so often, either on a newer engine, OR after the full tear down/ clean/ rebuild.
But you seem to want to try it, and I've done it several times (I am planning on doing the full tear down clean in the next 2 months) I think it helps a little.
Yes, do it prior to an oil change. You do run the risk of fouling your plugs, but I've never had any troubles.
There is the FAQ link for the How-to from the
Main Site That will get you started. I do it a little differently though. More simple.
How I do it: Get a piece of aquarium tubing, ($2 at WalMart for MORE than you would ever need). Cut a piece about 2-3 feet or so. Pop and prop the hood, start the car. Make sure you know where your throttle is and that you are able to rev the engine by hand from beneath the hood.
Open the SeaFoam/ Berryman's B-12 can and set it somewhere stable on the engine near the vacuum ports. (I usually use the battery) Stick one end of the hose all the way down into the cleaner can. The next step takes some juggling... Pull the vacuum hose out, you need to hold down the black round seal with your fingernail, and then pull up on the hose CAREFULLY! The seal and hose can be brittle.
Now the juggling. As soon as you pull the vacuum hose out the engine will want to die, so get on the throttle and rev it up a little. Now take the other end of the hose and put it into the open port and inch or so. Rev the engine up until it is running smoothly with no risk of killing, and you can see the cleaner flowing. The engine will suck the cleaner in VERY quickly, so be careful or the whole can might be gone quickly. Do 1/4 - 1/2 of the can in one port, replace the vacuum hose, then do the other.
Once you've run the cleaner through shut down the engine. Let it sit for a while, an hour or overnight. The theory is that the cleaner is in there soaking the crap off... Once you start it up, it will run rough for a few minutes and there may be some extra smoke from the exhaust. Mine did the first time or two I did this, but hasn't much since. I'm thinking that this sort of cleaning only goes so far, and everyone's experience on this site is similar. But I've done it as a substitute for the full cleaning, and figured this method was better than nothing.
It doesn't hurt anything as far as I'm aware. It also is only a light cleaning, certainly not complete.
Good luck!
