Seafoam OR Marvel Mystery oil?

Discussion in 'Engine Performance + Maintenance' started by Wilecoyote, Oct 26, 2020.

  1. Wilecoyote

    Wilecoyote I'm Awesome

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    Which? where?, when? and why? I apologize if this has already been discussed.
     
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  2. 454cid

    454cid Sooper Pooper

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    I usually add a quart of Marvel Mystery Oil when I change the oil in my 454. When I had an issue with unusually high oil pressure and a tap, I then added some Seafoam. It took both to remedy the issue.....I think it was waiting too long to change the oil.

    I'm pushing 300k miles.
     
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  3. thegawd

    thegawd I'm Awesome

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    Iv used mmo in my high mileage Burb many times. I also had a tap when I first got the truck almost ten years ago. Open the label and theres some very vague instructions.... when it was tapping I would add something like 1/4 quart, drive the truck for a week and then change the oil. It was messy terrible oil changes. Eventually the knock went away and the oil changes were normal.

    Iv made this a part of my routine maintenance every spring. My engine is all stock and never been touched. Purrs like a kitten and gets right around 17 miles/gallon.

    Iv only used seafoam in my 10hp 1963 johnson outboard motor when it was acting up. I mixed it up in the gas to its max dose and it made an instant difference. I was burning regular non ethanol gas. this engine sat in a basement for 30 years right after it was professional maintained. It started on its first pull. Now I cant find regular nonethanol gas and burn supreme in it now, it runs just like that day when I put seafoam in it, just like a top, best it's ever run.

    Those are my only experiences with those products.

    Al
     
    Last edited: Oct 27, 2020
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  4. df2x4

    df2x4 Domestics only.

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    Neither for me. I'm of the opinion that most "fix in a can" products are unnecessary at best.
     
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  5. Pinger

    Pinger I'm Awesome

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    Yep, wherever possible, preventative over remedial.
     
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  6. Wilecoyote

    Wilecoyote I'm Awesome

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    I put a few ounces of MM in the gas tank on my B&S 24hp lawnmower a week ago and it runs smoother and quieter. The engine has 178 hrs. on it and it works hard chewing and blowing the leaves into the natural areas in my yard.
     
    Last edited: Oct 27, 2020
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  7. 67GMC

    67GMC Newbie

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    I've used both. My scan tool showed a bad O2 sensor and it was running in open loop most of the time. So I changed the O2 sensor. It seemed a little better. I did Seafoam a few days ago. No adverse effects but not much improvement to the bog down it had when cold.
    I just replaced all 8 spark plugs yesterday. Found some NOS AC Delco plugs for $10/pack for 8 plugs. I drove for about 2 hours and I think it's great when warmed up but still hesitates a little pulling out of driveway if not warmed up. We'll see how it does with the weather staying cool hear for awhile. MMO I've used on my Jeep. Never really noticed any improvements but nothing worse either.
     
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  8. 96-2D-Hoe

    96-2D-Hoe I'm Awesome

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    I use MMO when I fill right up with gas. Quietened my screaming fuel pump a couple years back and I still haven't changed it.

    And I sometimes use 1/3 can seafoam in the engine oil for a couple days before I change it. That and cheap synthetic with some quick oil changes has made a huge difference to what was a very noisy lifter.
     
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  9. 96-2D-Hoe

    96-2D-Hoe I'm Awesome

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    Try cleaning the MAF sensor with MAF cleaner
     
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  10. Wilecoyote

    Wilecoyote I'm Awesome

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    My fuel pump whistles like a supercharger. It was like that when I bought it last year.Gonna do the MM soon.
     
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