MMO vs SeaFoam (for crankcase)

[FastSUV]

This thread is only to discuss the use of these two additive in the oil & not fuel or intake...Everyone knows SeaFoam is about the best intake cleaner & MMO is wonderful in the fuel tank.

BUT which is safest & best in the oil??? They strike me as similar products that might yield similar results in the crank case but of course the seafoam is more solvent-like and requires much less be used in the oil to do its job...

thought, comments, experiences?

Here is the page for SeaFoam - I have used it for 10yrs in JetSkis & intakes on vehicles but never in the oil. I was always too chicken to use in the oil just like MMO LOL:

http://www.seafoamsales.com/technical-information/gasoline-engines/index.html

 

[saberz]

For normal OCI use, MMO can be used for the full length. Seafoam is best kept for under 1k miles if not less. Seafoam is a harsher(not bad) cleaner and I wouldn't want to run it in the engine for to long.

I would use MMO for the full OCI, then throw in the Seafoam some 500 miles before the oil change.

 

[EricF]

I've used both MMO and Seafoam in the crankcase.
I've used seafoam in the transmission as well, I usually leave it in for 500 miles and then do a transmission flush.

MMO in the crankcase, gently cleans the gunk up, and helps quiet the engine down just a itsy bit, to me it idles "easier".
I use MMO with my synthetic oil changes, I don't use it all the time, usually twice a year, or if an engine seems pretty dirty.

I wouldn't leave Seafoam in long term, but short term has worked well., but MMO to me is perfectly safe.

MMO is more of a favorite due to the cost (and smell!)

 

[addyguy]

Seafoam is much 'harsher' - it's designed to only be used for short periods, in small concentrations, as a cleaner. AFAIK, it has no AW additives in it at all.

MMO is designed to be used, 1 quart at a time, for a full OCI. It has a small amount of AW additives in it to protect the engine, and be a 'part' of the lubricating oil.

I'd use the MMO, as it is safer. I'm using some thing similar to it, Wynn's Engine Tune-Up, for my full winter OCI to aid in cleaning.