Seafoam Use

wallychaser

Seaman Apprentice
Joined
Aug 21, 2011
Messages
30
Greetings, I have a 1999 Johnson 150 Faststrike Ficht ,runs excellent. I use only premium grade gas, should I use seafoam (spelling?) as well? This was recommended to me by a fellow boater. Thoughts?

Nick
 

jbjennings

Captain
Joined
Jul 18, 2007
Messages
3,903
Re: Seafoam Use

If you run your motor regularly, I would use it maybe every 10 tanks or so. If not, I'd use some stabil.
There's no reason to run seafoam every tank. Are you running the premium because it has less ethanol? If the ethanol content of premium is the same as regular, I'd run the regular. There's no other benefit that I know of.
JMO,
JBJ
 

Bob_VT

Moderator & Unofficial iBoats Historian
Staff member
Joined
May 19, 2001
Messages
26,019

archcycle

Chief Petty Officer
Joined
Sep 21, 2009
Messages
647
Re: Seafoam Use

Sea Foam gets recommended as a carbon deposit cleaner a lot but doesn't get much credit for being a fuel system cleaner. You should definitely run a can through every few tanks and also use a regular ethanol treatment like Stabil Marine. I'd say just run Sea Foam every tank but that would get expensive at their recommended 1oz/1gal when a $10 bottle of Stabile Marine lasts 80 gallons.

There's no positive to running "premium" fuel in a motor not designed for it. Premium is a marketing word it doesn't mean that grade of fuel is better. It is higher octane which means it's harder to make it blow up which is useful in higher compression engines to prevent early detonation. The piston compresses the air/fuel mixture then hits it with a spark. If the gas is too easy to blow up then the compression alone in a high compression motor will cause it to ignite before the spark. The two fuels are just for two different applications. You won't hurt anything but you will spend a few extra dollars at the pump and won't see anything for it.

That said- carbon deposits slowly build up in the combustion chambers. These deposits eventually create hot spots that cause early detonation. The solution there isn't to use a higher octane but to clean the carbon deposits out.
 

archcycle

Chief Petty Officer
Joined
Sep 21, 2009
Messages
647
Re: Seafoam Use

My motor is a perfect case study in why you need to run decarbing solutions regularly-

before cleaning by hand:
IMG_1854.jpg

after cleaning by hand:
IMG_1730.jpg

And you can bet your *** I don't want to have to do that again :D
 

3899

Seaman
Joined
Jul 17, 2005
Messages
68
Re: Seafoam Use

I'm no fuel expert, but from the articles I've read, the rule of thumb is not to exceed 10% alcohol. Ethanol is alcohol. The reason to run a higher octane is it could contain less ethanol than 87. 87 is the only octane that "has" to have 10% in it. If you have E10 in your tank, you have 10% already, and the vast majority of fuel treatments, incuding stabil and seafoam have some form of alchol in them to help with moisture and you now have more than 10%. Alcohol is tough on plastic fuel tanks and eats fuel lines. (I think it's harder on fiberglass tanks.) I don't have access to marine fuel, but if you do, it may be worth using, then you can add seafoam or stabil etc. cause I believe it has little or no ethanol. Also only put in your tank what your going to use in a few weeks, cause alcohol based fuel draws moisture. Cars can get away with it longer because newer ones have closed unvented systems. I am a firm believer in Seafoam. But I think it too has to be used in the right content. In my own boat, (Ranger with 150hp Evin '86) I went to 91 octane with no additives, and (I believe) it starts faster and runs smoother. (It may just be wishfull thinking).
 
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