I have a 90 420sel with 121k on the clock and all of a sudden I developed a rather disturbing lifter noise upon replacing plugs/wires/dist cap & rotor. I think there was a little bit of chatter all along from 100k when I bought the car to present, but now seems to be much worse. I have had the cam checked out and have a timing chain job done about 6-8 months ago. I have gone by many recommendations to go with 15w50 mobil 1 synthetic oil. That has helped the noise quite a bit, but it is still there. It seems to less noticable as you pick up speed in the car. One mechanic from the old school has advised me to drain down a little of the oil and add a bottle of Marvel Mystery oil. He said he had used it many times where lifters were noisy and in every case it stopped the noise almost completely if not completely. I have done a search and read several posts on the oil, but have not seen any on the gas engines. Can anyone give me their experiences/opinions on this and will it help. I do know eventually I will have to do some work on the lifter/rockers/cams, but unfortunately I am not ready for the repair this soon. Thanks to all who reply.

I like to use MMO on the cam/lifters/etc of a car that has been sitting for a while that I'm preparing to start. I also had a '72 Bronco with pretty severe lifter noise that a pint or so of MMO completely silenced. Of course, your results may vary, and you don't want to use it to "quick fix" a potentially serious problem. Mobile 1 should give you similar results, so if it didn't fix your problem you might need to dig deeper into the cause.

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J.B. Hebert

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Current Vehicles:
'76 Ford Bronco
'78 Volvo 262C Bertone V8
'80 Alpina B7 Turbo Coupe (For Sale)
'94 Ford Explorer
'95 Mercedes E300D Sportline+

I have a diesel however when it was clattering a Mercedes tech
said to use the Marvel Mystery oil and get it good and hot and run at high RPM's, which would clean up varnish & shellac deposits
The procedure worked Marvelously.

How much MMO did you use...1 Quart in place of regular oil?
RSL

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RSL007
1999 ML430
2001 C320 Sport
2000 SAAB 9-5
1998 E300DT
1998 C280sport
1991 300D
1991 350SDL
1982 300DT
1972 Porsche 911 Targa

used 1 & 1/2 qt's Cars capacity is 8 & 1/2 qt's

MMO is a water displacing oil great for air tools. I sure don't want any in my MB engines.A good high detergent oil like diesel rated Delo 400 15/40 might help Iv'e been using it in my diesels and my 500 Se quieted down the SE a good bit.I may change to another Dino oil like Castrol now that the Dellos done it's clean up job............

William Rogers.......

I'm totally with William on this. There is a can in my shop close to where I keep my air tools. Air tools are the ONLY things I own that will ever taste it.

In the distant past I have used it to decarbon various engines. But that was in the days before motor oil formulas underwent such drastic improvements.

I'm curious, what has been the oil change frequency on this car?

Have a great day,

I bought the car when it had exactly 100k on it. I immediately changed the oil in it to Mobil synthetic. My experience with Mobil synthetic is that you can typically go a bit longer on oil changes than with regular oil. I have made a practice of changing it between 5k-6k. I have checked with my local MB dealer and they recommend with synthetic oil changes at 7500 miles. The car does not seem to use a drop of oil in between changes.

I think that you now have the car on a good oil change schedule given the oil that you are using. I expect that the previous owner was not so dilligent.

Using the MM will really do nothing for you. A few oil changes of the Mobil One will do as much cleaning as can be done. If you still have the ticking, you might do a quick change or two with a super high detergent oil such as Delo 400. This is designed especially for diesels so it has very high detergent content to accomplish soot dispersal. It is also certified with the latest gas engine rating.

Since it is much less expensive than your normal brew, you can drain the engine while hot to get as much crud out as possible, put in a new filter and a fill of the Delo. Run it about 500 miles and change again while piping hot. This will get out the most gunk. Then go back to your synthetic brew with a clean filter.

This is the best and safest way to deal with a gunked engine. Using non lubricating solvents to clean an engine is risky.

Best of luck,

No great mystery.

MMO is mostly kerosene.

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1986 300E 5-Speed 240k mi.

The term "lifter noise" is misleading. What you are hearing is cam, valve and rocker arm noise. This could be due to failing hydraulics in one or more ball studs, but also to worn rocker arms, cam lobes, or "hockey puck" shims. Suggest you pull the cover off and find out what's going on. And also check out the plastic pieces on the oiler tubes.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

MMO is widely used in sailboats as a gasoline additive in old Atomic4 engines which were designed to run on regular leaded gas. Seems to work. I've never heard of anyone adding it to the oil.

Well, if you read the container MMO is in, it raves about the use in the crankcase. Maybe it is all smoke and mirrors... maybe not. I put in a quart last week in my oil change using Mobil Delvac 1300 super... for heavy diesel use....put it in my 98 E300dt with 90,000 on the clock. Damn if it didn't seem to run quieter. Maybe I heard what I wanted to hear. But, I have decided to drain it after 500 miles and just refill with the Delvac 1300...10W-40.
I think MMO psychology is to have you think a wonderful solvent is sloshing around in your engine dissolving all varnishes and gums, all deposits disappear, metal surfaces are bright and shiny etc, etc. Rislone seems to be very similar in their description of their product.
Larry Bible is probably right....frequent hot changes with a good grade of oil is probably as good as anything. But everybody out there is looking for that magic elixer for the gas or oil.
Maybe if I mix a little MMO, Risilone, red-line additive, ATF, cetane-improver, anti-gel, BG conditioner and JP4 jet fuel...shake it up, put it in a 1cc syringe, I could sell it for $19.99 as the ultimate diesel additive. So who would know?
rsl007

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RSL007
1999 ML430
2001 C320 Sport
2000 SAAB 9-5
1998 E300DT
1998 C280sport
1991 300D
1991 350SDL
1982 300DT
1972 Porsche 911 Targa

An oil rep. I trust once said, "if you need to put all those additives in your oil, why do you buy that oil?"
Stick with good oil and change it often (and hot). If everybody did that, the car makers would be in serious trouble.

Here's what's really in it:

http://images.shipstore.com/ss/images/mav/mavmmoMSDS.pdf

Mineral spirits, napthalenic petroleum distillates. No kerosene (paraffinic petroleum).

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Norm in NJ
Next oil change at 230,000miles