Seafoam vs MMO

Lily'sDad

Lily'sDad

GMC, They Said
Senior Member
I know, this has been bashed around countless times. And countless times, it comes out with 50/50 replies.
Which is better Seafoam . . . or Marvel Mystery Oil? Which one do you put in the gas can and which one do you put in the crankcase? Do you have any objective proof for your choices?
 
I've used Seafoam when I think a carb is gummed up or dirty. Helps sometimes. Or definitely helps when a known problem with bad gas.

Never tried Seafoam in the oil. Guess I would if I knew I had nothing to lose.

Never really tried MMO. Only so many magical formulas I keep on the shelf.

Does it magically clean all carb problems. No. But the first thing I try if I know things sat around a while.
 
I've always used Seafoam. Never tried MMO. No reason for it. Just the way it's worked out. Several years ago I had a Craftman rider that started spitting and sputtering around. Dumped a little more than the recommended amount of Seafoam down the next two tank fulls and the problem went away to this day. Guess that doesn't really prove anything one way or another.

jhn9840
John
 
Tried MMO in a well worn generator once. But it was beyond help. Drinks oil like I do coffee. We have dumped all kinds of stuff in it to slow the drinking problem, so far it was a strikeout. 7500 hours on it though. Boss got one to 10,000 hours before rebuilding. Which gave another 4000 hours before refusing to run nice.
 
I've only used Seafoam auto tranny treatment and that worked good.
The MMO has been used mostly in Diesel equipment and the results have been excellent for removing carbon deposits, sticky injectors, and I feel better knowing that it's in the fuel as an added lubricant. Sure wouldn't hesitate to use it in gas engines with gum and carbon issues.
 
The carb on the Wisconsin on my Hobart welder was badly varnished when I bought it. Disassembled the carb and soaked overnite in straight Seafoam, next ,morning it was all cleaned and is working good after 3 years.
Had an 8 HP Briggs with a sticking intake valve. It would run but it would hunt due to intake air being forced back thru the carb. Fed it a heavy dose of MMO thru the intake at full throttle, chased off a lot of mosquitoes for about a minute and the hunt went away.
Mike
 
Seafoam as said above, never really used mmo, Lucas has always been my go to for use in oil, my truck gets Lucas in the oil every time I change it, and I use their power steering treatment as well.
 
I ran a 2008 E-350 work van with 167k on it and the transmission started shuddering bad when shifting. Got to the point that it would occasionally not move and then take off. Knew this couldn't be good.

Take it to my mechanic and he agreed. I mentioned about doing just a oil and filter change and see what happens. He said ok and said also lets add some "Lucas transmission fix" as well. He used it many times said good things about it. All the while figuring we had nothing to lose.

Long story short I ran that van another 15k miles without issue.

Oil change, filter, Lucus, luck ? I don't know.
 
I watch the velocity channel and one time caught Wayne Carini mention using MMO in an old engine that was stuck. After soaking the cylinders for a few days it came free. I have since heard him refer to adding magic oil to the cylinders, figure he is still using the MMO. I have used the sea foam to help clean up the fuel system, sticky throttle plates etc. I like both for fuel and MMO for the oil system. Don't use sea foam in the oil, afraid it would be like adding kerosene or something and thin it out too much..
 
I too use both.
Seafoam in the gasoline, and MMO in the crankcase oil, BUT, I have added some MMO to the fuel lately on some "new" tractors that I just brought home.
We have an ag tractor/implement dealer in town and I know one of the mechanics there. He has been "wrenching" for close to 50 years and told me they used to use Stabil in fuel and still had issues with the ethanol. They switched to Seafoam and no longer had issues.
That was a good enough testimony for me!
 
Seafoam is what I use for gummed up carbs. Works great.

Several years ago I had a guy call em with his car broken down. It was pouring rain and the car just bogged down and quit. I pouredin a whole can of Seafoam and it bucked and snorted till it pulled it up through the lines and then started running great. The next big storm we had it stopped running again. He was at a friends house and they pulled it up in the garage. When I got there the smell of gas was overpowering. I pushed it back outside to look it over. The whole top of the gas stand was rotted out (yankee car) when he drove it in the rain it put water in the tank. I told him to keep a can of Seafoam in the car and pour it in when he drove in the rain. He drove it another 2 years (somehow without blowing up) and finally had me put a new tank in it. It was so rotted there was nothing to attach the new tank to. I had to rig new mounting points and he drove it another year before the rear struts came through the trunk.

If I have an engine that is going to have to sit a while I put MMO in the tank. Keeps it from sliming up.
 
A lot of great reply's but I'll put in my .02 so that you can poll the answer with all the other reply's.

MMO: I run a very little bit of MMO in my gas if I am forced to purchase gas with ethanol in it. Specially if the engine will be sitting for any period of time.

Seafoam: Seafoam is a treatment and is cleaner, I do not add seafoam to my engine oil or to my fuel. Seafoam is great from removing carbon and I find it works best when you flood the intake system with it as per the instructions are written.

There is no need for oil additives other then zinc to your engine oil if you keep your oil changed your engine will stay clean , the only build up in the engine that cannot be avoided is carbon and carbon comes from use and or bad gas or or even blow by of engine oil. I bet the MMO also put a few deposits in there as well, so every blue moon or so or when I feel the engine has seen alot of hours I'll give it a good wash down with some seafoam to clean it up.

I will also seafoam on unknown to me engine before I start working on or repair it, I have had one that was sputtering and popping through the exhaust pretty bad and then I did a few seafoam washes and cleared it up completely so I find that straight up is the best way to use it.

If a carburetor is gummed up ,I take it apart and clean it. Because even if it breaks up that crap in the float bowl where is it going to go?
 
Reading online says that seafoam is:

50% light hydrocarbon oil (pale oil);
30% petroleum naphtha;
10% isopropyl alcohol;
10% water.

So you have water, alcohol, naphtha (a solvent) and some pale oil to float that stuff in.

I'm not a fan. Falls into all the other oil additives for me. Dad always called them snake oil.
 
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