First let's understand why Seafoam smokes, it's because it is very dirty itself. You see it is mostly kerosene-a light fuel Oil. All oils will smoke. It's formula has not changed in 70 yrs. It is ok for 2 stroke engines and old cars but not modern cars. Seafoam has little effect on carbon full strength, even if you leave it in it for a day. The strongest solvent is Acetone half as strong is toluene and xylene, and quarter as strong is naphtha. But the best product to clean carbon valves is P.E.A.
I have looked at most products stating it cleans carbon and they are mostly solvents or alcohols. Many others have very low amounts of PEA. The exceptions are Redline si1 28-34%PEA, a spray but $16. Techron ,the founder of the effects of PEA ,old formula was 30%{6 or so yrs ago}. Now its 20-25%. Comes in a bottle but stores give BOGO which brings price down to $5/bottle. Gumout Regane complete. 12oz 10-30% $8, Lucas deep clean is the same but only 5.25 oz bottles. CRC GDI IVD 12oz spray, 10-20% for $20. My last choice is Royal Purple Max Atomizer Fuel 6oz for $8 with 15% PEA.
So how bo I use the bottle I looked at the berryman can 6-10% for $40. I saw the hose and made my own. I used the oxygen supply hose(like they put on you in a hosp).you can use fish tank hose. Then I added a restrictor, the little red plastic(tube) sprayer that comes within most cans, it fit tight into my oxygen hose. if not, use some glue or epoxy. I closed one of the 2 nose holes. So now I have a restricted hose with one air vent. The air vent controls the speed it pulls the liquid out of the bottle. Open, it pulls the liquid fast put my finger over it it slows down. This way I do not stall out the car. I put one end in the open bottle securely wedged in the car. The other end I bought a surgical injector for the v shaped stopper that comes with it. The plastic red tube fits perfect into it. I epoxied the tube to the stopper, therefore it can't be sucked into the engine. I remove the vacuum brake line and jam the stopper into it.
There is know no vacuum leak and when I turn on the engine it will suck from the bottle,Note CAR IS AT OP TEMP.. If the tube iS NOT past your MAF or MAP sensor remove it and seal the hole, or use that hole instead of the brake line. Now I needed a way to keep the car running at 2000rpm. For this I got a stick about 2 feet long i put it btw the gas peddle and my seats. Then I move the seats up until it hits 2000. After this I put the other end of the hose in the bottle, cover and uncover the air supply hole. In about 20 minutes it is done. The I rev the engine 2 times to 3500. Next I let it heat soak for an hour. Then take onto the highway and drive at 60 mpg for at least 10 min. You might see smoke thru out this whole process. Unlike Seafoam this smoke is not from the light oil, but from the burning carbon. Note, even though you are using one of the highest consentration of PEA, it will Only remove a small amount of carbon. This is a preventative procedure. If your car is new and you do this every 10k your valve will be like new. If you waited to 30k, like me, it will never be 100% clean. If your waiting to do this and you never did it before and your car has over100k I would suggest manual cleaning.
A couple of final thoughts, do an oil change after this treatment. Next only use full synthetic oil, it produces less blow by gases=less carbon. Your cars engine light might come on and your car can run rough until it resets my Toyota takes up 100 miles, my Kia about 20 miles. I also don't recommend you use more than one bottle at a time or more than at each oil change. There is Some viewpoints that too much can damage you cat. This probably will have a negligible affect on gas mileage (unless your valves were very dirty and you did manual cleaning).
running bottle of redline sl,1 in 18 gallon tank 98 Buick LeSabre..got it near empty. That about 13-14 gallons their. Got3,100 miles on old oil now. So planning oil change end of this month after this tank is used.
