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Anyone use Seafoam?

steelhd

TJ Enthusiast
Jan 1, 2019
156
Eastern WA
I run Seafoam through the gas tanks of my vehicles whenever I think about it. So maybe every year or two. Its not a magical elixer like some would have you believe but it doesn't hurt anything either. Maybe does some good. Where it definitely seems to do some good for me is in the fuel for the 1992 two stroke outboard on my boat.
 

Chris

Administrator
Staff Member
Sep 28, 2015
38,128
Salem, Oregon
Not in my 2 stroke Merc. What that says, or doesn't, about its use in modern efficient 4 stroke engines I don't know.
I've never actually used it, so I'm just speculating.

In my mind, if it comes in a can and goes in an engine, I'm immediately suspicious.

I could see something like this working in a more primitive 2-stroke engine though.
 
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Fixer6

TJ Enthusiast
Oct 12, 2018
243
Kingwood
I know some guys that swear by it. They claim it cleans any gunk out of the engine, and then you just change the oil and watch what comes out. I get that certain places get hotter than others where oil travels through, and there may be some grunge as a result. I guess it’s the same for dirty fuel going through the system as well. I totally agree about two strokes, especially those with exhaust valves.
Growing up we had a 1959 50hp Johnson Seahorse (4 piston two stroke) on the back of a 1960 solid mahogany boat. Every spring and fall my dad ran Marvel through the motor. It’d smoke like all get out while he did it, but I can’t remember us ever rebuilding it. It was still running last year when I sold it.

F95B0006-D0F5-4EAE-B516-5D340C734618.jpeg
 

skrelnik

TJ Addict
Supporting Member
Jan 10, 2018
1,090
CT, United States
Seems like snake oil to me.
Same here, but I hate assuming and speculating. There must be some Independent tests floating around.

Found one by Chris Fix. Seems like it works a little, but will it work on the 4.0? I have never read of anyone doing a carbon cleaning on our 4.0, where's my German owned cars needed to have the valves hand cleaned around 100k miles.

 

jazngab

TJ apprentice
Supporting Member
Aug 23, 2018
703
Montgomery County, PA, USA
I just used a can last week a few days before my oil change. Did half the can poured in the engine and half in the gas tank. First time trying it. Not sure if it worked but my engine oil was pretty black when I drained it. My last oil change before that was about 2500 miles and 8 months.
 
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toximus

TJ Addict
Supporting Member
Mar 29, 2018
2,248
Northern WI
I had an O2 sensor that wouldn't turn off for about a year (it was down stream, so I didn't care) after running seafoam through several tanks of gas it turned off. And then after enjoying it for a month it turned back on intermittently and I replaced the sensor.

The other experience I had was a Jeep with a surging high idle. I did a bunch of stuff all at once to clean up the intake including pouring seafoam down the throttle body. No more problems at idle.

So is it some magical fix? No. Does it maybe help? Maybe.
 
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SteveBarrus

Member
Supporting Member
Jan 14, 2019
84
Washington
I have used Seafoam and Marvel Mystery Oil in all my cars for the past 30+ years. Seafoam will remove moisture, smooth the idle and things seem to run better. I have eclipsed 350000 miles on all my vehicles before sending down the road. I cant guarantee that it is the Seafoam and MM oil but I will continue to use them.

My first experience with both was a 1967 cougar that had been sitting for 5 years. Changed fluids, new battery and could not turn engine over. Pulled the plugs and injected SF & MM oil into each spark plug hole let set for week (recommended by my dad). A week later turned key and the engine spun blowing all excess oil out of the open plug holes (dad also taught me about hydraulic lock and why to leave the plugs out when turning engine over). Poured a 1/2 bottle of each in the tank and 1/2 in the oil started her up. The car ran rough as would be expected on any car sitting that long but with in 2 days was purring. We did not have to tear the carb apart. The combination did the job. Changed oil after 7 days and drove the car all through high school. I continued to add 1/2 bottle each to the engine oil after each oil change. The old 289 ran to beat the band. I always credited the additives for keeping me from tearing the engine down.

Both products have been around a long time.
 
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Goatman

TJ Enthusiast
Apr 23, 2019
507
Upstate NY
Did a LOT of good on my 2 smaller diesel tractors. 4 cyl 25ish hp. I have to run that crap ethanol gas here in NY so I add a mix of sea foam, Marvel's, and Lucas top end (8 oz. total) per full up. Otherwise things start to run like crap. I'm pretty sure I get a few oz. of water with the fill up too. Every honest station admits to water in their main tanks. It does help with this gas, tho I think take out the ethanol and I wouldn't need the option any more.
 

Equilibrium31

TJ Enthusiast
Supporting Member
Apr 7, 2018
943
Burnsville, MN, USA
Not in my 2 stroke Merc. What that says, or doesn't, about its use in modern efficient 4 stroke engines I don't know.
I take Scotty Kilmer stuff as a grain of salt, but from what he said about it, Seafoam is well designed for 2 stroke engines, but you'd want a nitrogen-based cleaner for a 4 stroke engine:

Never used the stuff myself.
 
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xackley

TJ Enthusiast
Seafoam is good for a final clean on the idle circuit in carbs. My yamaha 650 gained 500 rpm at idol after 10 miles with seafoam, and that was after 3 cleanings trying to find the problem. The goldwing 1100 it smoothed out the idle and equalized the vacuum. Saved me from pulling 4 carbs that had set for too long.
The thing about seafoam is that it will fix a small fueling problem.
It will also clear out small valve/ring leaks if the leak is caused by carbon or other gunk. Dump a little in the spark plug hole and crank it over without starting, let it sit over night. I gained 20 lb in compression on one side on my r75/5 with that method. Evened them out within 2 lb.

When I buy a used vehicle there is no down side to adding a some to the gas tank. I fill it up, drive until over half the tank is empty, then add about 10 oz of seafoam. As of yet I have seen it do anything to improve performance on a fuel injected engines, but it would be my first option if I thought a miss was caused by a bad injector before touching a wrench.

Don
 
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Farmergreg

Just a "Web Wheeler"
Supporting Member
Mar 25, 2018
530
WC Indiana
Did a LOT of good on my 2 smaller diesel tractors. 4 cyl 25ish hp. I have to run that crap ethanol gas here in NY so I add a mix of sea foam, Marvel's, and Lucas top end (8 oz. total) per full up. Otherwise things start to run like crap. I'm pretty sure I get a few oz. of water with the fill up too. Every honest station admits to water in their main tanks. It does help with this gas, tho I think take out the ethanol and I wouldn't need the option any more.
Loving it!
Big oil has done an excellent job "educating" the consumer!
 

Goatman

TJ Enthusiast
Apr 23, 2019
507
Upstate NY
If by "educating" you mean providing a product that actually works for specific purposes, then yes they have. One tractor sounds like the injector pump is ready to blow up. Add a few oz. Of Lucas top end fluid to the fuel and it runs smoothly and quiet. How 'bout that education?! Is a lot of this stuff snake oil? Absolutely. Is some of this stuff effective? Obviously so. I am far too cheap to spend money on products that give no benefit.
 
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