I've heard that this is a good way to clean your engine. Anyone try it or normally do it?

"The best way to clean carbon build-up out of your engine is NOT to take the car out and run it as hard as you can. This only results in meetings with local law enforcement personnel, and doesn't do much for cleaning out carbon.
If you really want to clean the carbon out of your engine follow these simple steps. Fill an empty soda bottle with water. Remove your air cleaner. Start your engine. While using one hand to control the throttle, trickle the water into the carb or throttle body with the other while holding your thumb over the bottle opening. Keep the engine rpm's up so that the engine doesn't die. Make sure that you don't pour the water in too fast! Water doesn't compress and if you pour too much water in, severe engine damage can result! White smoke from the exhaust is normal. If you have a port fuel injected car, you obviously won't be able to use this method, but I have had success with connecting a vacuum hose to a port at the base of the throttle body and sticking the other end of the hose into the bottle of water. The vacuum of the engine will suck the water in, creating the same effect. This will clean out even the most stubborn carbon, by 'steam cleaning' your cylinders."

Umm, that sounds weird.

I get a low weight oil, like 5 or 10 weight, and a can of that mystery oil. Drain all the old oil in your car, put in a few quarts of the lightweight oil and a can of the mystery oil, then just let your engine idle for about 20 min, maybe rev it up a couple times.

Then drain that lightweight stuff out, watch some gunk follow it, and let it allllll drain out, like for 20 min or so.

Then fill with regular oil, change filter, works for me.

Use a spray bottle instead of trying to pour it, makes it GW proof. You can spray at the throttle body plate while holding the revs up.

I've got a bottle of this engine cleaner. It works from the inside. It says to pour it in and idle it for about 10-15mins. Then drain.

Got this stuff from a mechanic and he says that the dealerships charges $60 for an oil change with this stuff. Makes the oil stink.

I just use like half a can of Seafoam.  Pull a vacuum hose off the intake, running it through the hose while the car is idling until the car konks out.  Then let the car sit for a few minutes, take it for a hard drive and it will smoke like crazy, until smoke is gone.  The oil will need a change afterward though.  Seafoam works wonders.

Marvel Mystery Oil was good for the older carb type non pollution control engines. I'd not add it to gas on today's engines but an eighth  of a cup or so in the oil wouldn't hurt. (not too much, though.) Run it for a couple of days then do a normal oil and filter change. While you're doing that add a can of Techron (any Cheveron station) to your gas. Follow the instructions on the bottle.

It won't clean out all the sludge but it will improve things a lot. Techron will blow the carbon off the valves and clean the injector system as well as the upper cylinder and heads.

Brian "Red Kool-Aid drank for one and all" H. says:

I just use like half a can of Seafoam.  Pull a vacuum hose off the intake, running it through the hose while the car is idling until the car konks out.  Then let the car sit for a few minutes, take it for a hard drive and it will smoke like crazy, until smoke is gone.  The oil will need a change afterward though.  Seafoam works wonders.
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Wow, Seafoam. Wouldn't all this Seafoam in the system harm the cadillac converter?