You want the motor treatment its ok to put it in the oil,I've none it to cars and motorcycles,The can tells how much to use in oil and gasoline.You don't have to change the oil after you use it in the oil.

The Material Safety Data Sheet (MSDS) for Seafoam says it contains about half "pale oil" (20w motor oil); about a third naptha, and about a sixth isopropyl alcohol. I say "about" because apparently there are two or three formulations differing slightly in their composition. Seafoam's website says it was originally developed in about 1942 to clean lacquer and varnish from clogged outboard carburetors. Let's look at these things.

Outboards of the era used premix, that is, gas mixed with oil. If someone poured a solvent into a carburetor to clean out the grunge, then started the outboard, it would be running with no oil and might be damaged. This is probably why Seafoam included oil. Naptha is not very different from gasoline, and in fact is sold as "white gas" or Coleman fuel. It also sold as lighter fluid and spot remover. It will dissolve at least some deposits, but so will gasoline. Isopropyl alcohol, also known as rubbing alcohol, is another solvent and will assist in dissolving carburetor deposits. It will also attract at least a little water and help move it through the system.

Four-stroke engines do not need oil in their fuel. Thus, the "pale oil" is of very little value. Gasoline is itself a very light oil and will provide plenty of lubrication for carburetor parts, especially as those carb parts normally run wet with gasoline anyway. Little comment is needed on the naptha, since it is almost indistinguishable from gasoline. Seafoam's website says it will remove small amounts of water, but goes on to say liquid water will need to be drained and that the Seafoam will not remove it. In any case, much US gasoline has ethanol (another alcohol) added anyway, and in quantities far greater than the small amount in Seafoam.

For use in engine oil, the little bit of 20W oil will have almost no effect. By the time the engine oil gets up to temperature, the naptha and isopropyl alcohol will have evaporated out, and thus will have essentially no effect either.

Seafoam has been around for a long time. It has a lot of believers and a lot of anecdotal testimony as to its effectiveness. But, as far as I have been able to find, there have been no actual tests of its effectiveness. The conclusion I reach is that it is unlikely to do either good or harm.

Yep you put in in the oil it cleans the engine and clutch,Put it in your car oil too it will run a lot better,If it a new car it will keep it clean.

Once again Bill writes without thinking. I have said, and on this very forum, that ethanol produces less energy than "pure gas." It is on the order of 3% less. That is, roughly, the difference between 60 mpg and 62 mpg. A difference easily swamped by other variables such as speed, wind, temperature, and so on. In short, without very careful measurements you will never notice the difference. The ethanol does raise the octane rating of the fuel, and I have also commented that it reduced knocking on a '79 Lincoln I used to have. I do not necessarily think ethanol is the "best thing that ever happened to gas," but at 10% I certainly do not think it is harmful. I can speak from first-hand experience when I say I have been using it for thirty years with no evidence of damage to any of my equipment.

Back when "gasohol" was introduced, people were cautioned that its use might loosen up deposits and dirt in the fuel system, and might result in clogged fuel filters. I think that is a pretty good testimonial to its solvent and cleaning abilities.

Bill is correct that I have never used Seafoam. I do not intend to do so, because I think it is useless. IT WILL DO NOTHING FOR A CARBURETOR THAT IS ALREADY CLEAN. There is absolutely nothing in it that can do a better job of dissolving crud than ordinary, clean gasoline can do. And until someone (yes, you, Bill) can cite a controlled test proving Seafoam works I will continue to believe it is useless.

Charon, I'd like to thank you for an imformative, unbiased "review".  I talked to my hubby about it, and he said he wouldn't use it except for a couple extreme circumstances either.  

I was more curious, because I see so many threads, people say something is wrong, and someone throws out "run some Seafoam through it" response.  I could have read their website for an hour and not gotten the information that you gave me.  My husband also knew more about it, although I hadn't previously asked him.

Anyway, as with anything like this, there will be some on each side of the debate.  And I appreciate hearing both sides.  That way, I can make an informed decision of my own.  

If your hubby and charon who neither one have ever used it say its no good its best for you not to use it.

bill67 wrote on 07/07/10 at 16:59:17:


Where did I say that my husband has never used it?