Just my .02
I would use caution any of you guys who have high mileage engines. Sea Foam does work great I have been using it for almost 20 years now, Fogging your motor, which is what most of this thread has been about is safe and will benifit you greatly. For those who have 100k+ fog the hell out of it, use 3 to 5 cans and stretch it out over a couple days. Fog it shut it down let it sit for a few hours then fog it again. By letting it sit for a couple hours you are increasing the effectiveness of the Sea Foam by allowing it to soak into the carbon, gum and varnish deposits in your intake, combustion chamber etc. and when you fog it again the layer on top comes off and you soak the lower layer and so on and so forth. While sea foam works, it does not do the job it appears many of you think it does. Even if you fogged 100 cans through a vac line it will not come totally clean. Your best bet there is to pull the upper intake and clean it by hand with some laquer thinner, an old towl and a couple sizes of nylon bristle scrub brushs. Fogging the system will loosen up and burn off the light stuff that hasnt been on there very long, but if you really want to get your intake clean you have to do it manually. If you have ever tried cleaning that carbon off you know there is no chemichal that is taking that off... Hell even with a scrub brush, thinner and razor blade, it is next to impossible to get that stuff off... I know I just spent 3 days cleaning my upper and lower intake, and I was rather miffed about the amount that I could not physically remove by hand. I promise if I couldnt force this stuff out of here, nothing in a can will take it away either. Using a strait solvent like thinner is much more powerfull than any thing you can use to fog your motor with. (what ever you buy designed for this has to be safe for o2 sensors,cats, and the rest of your motor) so while it is good its not "the best" you can use. I let my whole intake soak in a 5 gallon of thinner for a day and a half thinking that would at least soften up the crud in my intake... While it did make it alot easier to remove, even after soaking in solvent for at least 35 hours there was still quite a bit of scrubbing to do. I am not trying to burst any ones bubble here or any thing like I said sea foam is good stuff. But do not mislead yourself into thinking that you are really doing much. It smokes alot while you are fogging not because it is "burning" anything off. If that were true your cats would be trash in a matter of seconds. That is simply the sea foam burning. It is a oil based product but it doesnt burn as easily as fuel does, so basicly what you are seeing with the smoke is the same as you would see if you got some oil in your combustion chamber.. think burnt rings. it doesnt take much oil to create ALOT of smoke. It is not ta total waste like I said you are cleaning off ALOT of the surface muck that helps restrict airflow, as well as create alot of turbulance inside the intake, which does equal less power and mpg.
For you guys who are putting it in your crank case... BE REALLY CAREFULL HERE. if you have a high mileage engine, think long and hard before adding anything that might clean sludge deposits. As your engine wears down, gaps widen, clearances get larger, alot of times in a high mileage engine there is quite a bit of sludge, oil, varnish, and just plain yucky filthy muck. I have seen 2 times in my life engines get destroyed by cleaning out the oiling system. Almost 3 times but the 3rd person was smart and paid attention to his guages. The first time was my own vehicle. I had a 1963 Dodge D-100 with a slant 6. Wich is normally a bullet proof motor...Normally. Well I am 16 just got the truck, just got my license. I am broke, and wanting to do something cool to my truck. Back then b12 chemtool was about 2 bucks a can so I went and got a couple cans, some oil, a filter and some other stuff. So I get home I follow the directions on the can to a t. Pour it in, run it, drain it, fill and I am good right? Nope. The chemtool did its job, just as it said it would. It certainly broke loose all the gunk in my engine. Well all that gunk has to go some where and it does not liquify kinda turns into something that has the consistancy of peanut butter...the chunky kind... well Every singly push rod in the motor got stopped up, the oil pump got clogged, the pick up tube mesh got clogged.2 of the main bearing journals got blocked as well as the journals in 80% of my camshaft. It started out a little noisy, i got about a mile away and it started getting really noisy. I remember turning around panicky thinking... I wish this noise would just stop... It did... just like that. Stopped... Along with my engine. The second person a buddy of mine did the same thing, this time with sea foam. His wasnt so bad, just clogged up the pickup tube for his oil filter. He noticed 0 oil pressure and killed the motor and called for a tow truck. The Third person was a customer when I worked at a chevy service dept. Much the same situation only I dont know what they used to flush the block, they took it to a quicky lube type of place and got both their transmission (another bad idea for a high mileage vehicle) and engine flushed. The transmission made it (though 75% of em end up quiting in a few days or weeks after the flush due to lack of metal dust in the fluid, and the bands not getting the friction they need) but the motor was fried, the motor flush cleaned off some gunk that had formed around the front and rear main seals, when that gunk got cleaned off, the seals developed a bad leak. The person said they lived 9 miles from the lube place, in that 9 miles not only did all the oil they just put in leak out, but the motor siezed up cause it didnt have any oil.
Now I dont know everything and I am not a master mechanic or any thing. In fact just yesterday I couldnt figure out something and had to come and ask for tricks. But I have worked in the automotive service industry nearly my entire professional life. I have an associates in automotive technology and several ASE certifications. These are just my oppinions and I am not trying to sound like a know it all nor am I trying to disprove or offend any one at all. This thread just caught my eye. I like to read alot of threads just to see what kinds of problems people are having to see if I can add any thing to the conversation. Normally I dont have much to say as the mods and gurus are pretty quick to answer here and if my answer is the same as theirs... This time I have a slightly different take than most do. Sea Foam is snake oil, its good snake oil but it doesnt really do much. Your vehicle will run better while it is in your tank, not because its doin its job. but because they put additives in it that feed the combustion better giving you a little more power, and a smooth idle. As soon as you empty your tank and put more fuel in your performance goes back to normal. If I put any thing in my tank its either berrymans chemtool with HEST, or Lucas. These products do good things, again not as good as most of the public likes to think they do. But they do help keep yer fuel system clean. In this case they are cleaning off varnish, and gum, which is hell on valves, injectors, filters, pumps , and if the vehicle is a spare and doesnt get driven often, I have seen a couple of instances where this crud has completely blocked off a fuel line.
If ya have a lower mileage engine, Like the crate motor I am currently installing in my truck this kinda stuff is actually really good, and I plan on flushing the motor once every 3 months to keep it perfectly clean on the inside. Thats where these products offer the most help, keeping something clean. There is no sludge, or varnish or carbon, So If I remove it when all that exists are the easy to remove areas then my motor will stay clean inside.
I hope this helps some one, and prevents them from making a huge and potentially expensive mistake..
Oh yea here are some pics of my motor. I am right smack dab in the middle of it but it is looking really nice. Too bad its a cloudy day here this paint is so super sick in the sun... IT would look alot nicer with new accessories on it too... but I just spend 4500 on the motor im broke now... lol