Thread: Mmo
View Single Post
Old 12-12-2011, 09:15 PM   #14
Master Member
PlasticCarsRock is a jewel in the roughPlasticCarsRock is a jewel in the roughPlasticCarsRock is a jewel in the rough
PlasticCarsRock's Avatar
Join Date: Dec 2005
Location: Brookline, MA
Posts: 4,317

1995 SL2
Default Re: Mmo

Originally Posted by badbobby View Post
Yes--but my engine has 170.000--heard it is risky to start synthetic oil on high milers???
If synthetic causes any problems, you're already living on borrowed time. It is possible, but it is very unusual for synthetic oil to cause problems (it won't unless you're engine is in really bad shape. 170k is certainly high-mileage, but unless the oil hasn't been changed much, that's not high enough that the engine should be in "really bad shape". Personally, I would switch to synthetic unless you're burning a lot of oil (but if that's the case, I would definitely try an MMO soak--it shouldn't cause any problems, and it could help). I would get a quart of MMO and do two or three soaks, a few days apart, adding the remaining MMO to the oil, after the last one, and change the oil after 200-300 miles (if you consider that you're just topping off the oil, it's essentially free (other than your time)--schedule this so it lines up with when the oil needs topping off, and when you plan to change the oil)

Originally Posted by badbobby View Post
By deisel oil do you mean deisel fuel? in the oil pan??? Also why not piston soak? Yes I have heard a lot of good comments on seafoam. And yes walmart rocks on their prices on most oil products including synthetic oils.
No... he/she means diesel oil... oil designed and marketed to be used in diesel engines. While the detergents in diesel oils are not optimal for use in gas engines, they do tend to clean a bit better. Regular synthetic oil is still a far better choice, though.

Originally Posted by badbobby View Post
Thank you. In the far distant past I heard that marvel mystery oil was recycled trans fluid--have you heard this also???
No, that's not true. It does have similar properties to ATF, but lubricates better (ATF will also help clean out your engine, but while it is a lubricating oil, the lubricating properties are not sufficient for use inside an engine). Some people too cheap for MMO (~$3 per quart, IIRC) will occasionally use some (used) ATF instead, shortly before changing the oil. It does clean the engine (the oil is very dirty after doing that), but most people agree that it can do more harm than good).

As for synthetic vs regular/"dino" oil:

My '95 SL2 with a bit over 100k miles (ran like new, didn't burn oil, the rebuild was purely for performance reasons). Mobil 1 synthetic 5w-30 with frequent (perhaps excessive) oil changes. The mileage on this engine (while pretty low) was quite harsh--mostly short, stop-and-go trips with traffic, and a lot of really steep hills (NYC and Ithaca, NY):

No build-up, residue, sludge, etc, just a thin layer of clean oil on everything. An engine with 5,000 miles wouldn't look any different on the inside (the oil remnants on the outside of the engine is from a very minor cam cover leak).

The factory cross-hatching is still there, the cylinders are perfectly within spec in every way and there is absolutely no discernible ridge at the top of the cylinders:

(The coolant is an odd color because it has UV dye in it; that's not mold or algae in there.)

And a BMW engine that was not fortunate enough to enjoy synthetic oil:

I don't know the exact mileage of that BMW engine, but I've worked on several engines with 100-150k miles that looked like that (one that was even worse--had oil pressure problems).

Last edited by PlasticCarsRock; 12-12-2011 at 09:29 PM.
PlasticCarsRock is offline   Reply With Quote