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Oil weight question

OP
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Thread Starter #21
I looked repetitively and tried my best to find any indication of MMO being harmful in any way, and I just cannot come up with any source claiming its dangerous (used as directed). Some critics call it "snake oil" and claim it offers no benefit, but not one has ever said it did harm, as far as I can see. I am confident it would indeed thin the viscosity of a 10w-30 oil, and it probably aids in gentle internal cleaning over time.

Interestingly, the "nostalgia" aspect of it probably dissuades some from using it, due to fears that its only for classic cars or such. However, they claim:

Q: Is MMO safe to use in today's cars? Answer: Yes! Marvel Mystery Oil is completely safe in today's high-tech cars and provide the same benefits as it has since 1923-cleaner engines, upper cylinder lubrication, reduced acid and sludge build up, improved fuel economy, clean and lubricated fuel systems and many more!

Not trying to convince anyone, I am just adding to the conversation. I will likely try it once (after warranty) and see how it goes. Ultimately I don't think running a 10w-30 in hot TX is much different than running a 5w-20 in the cold north, which Fiestas have done for millions and millions miles without issue.
 

Lbrocato

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#22
I looked repetitively and tried my best to find any indication of MMO being harmful in any way, and I just cannot come up with any source claiming its dangerous (used as directed). Some critics call it "snake oil" and claim it offers no benefit, but not one has ever said it did harm, as far as I can see. I am confident it would indeed thin the viscosity of a 10w-30 oil, and it probably aids in gentle internal cleaning over time.

Interestingly, the "nostalgia" aspect of it probably dissuades some from using it, due to fears that its only for classic cars or such. However, they claim:

Q: Is MMO safe to use in today's cars? Answer: Yes! Marvel Mystery Oil is completely safe in today's high-tech cars and provide the same benefits as it has since 1923-cleaner engines, upper cylinder lubrication, reduced acid and sludge build up, improved fuel economy, clean and lubricated fuel systems and many more!

Not trying to convince anyone, I am just adding to the conversation. I will likely try it once (after warranty) and see how it goes. Ultimately I don't think running a 10w-30 in hot TX is much different than running a 5w-20 in the cold north, which Fiestas have done for millions and millions miles without issue.
I did put mmo in the gas once in 1974 super beetle and it ran rough. I might have put too much. But it never hurt it . I used up some of mmo and put in freash gas it ran well again.
 

Handy Andy

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#23
Not trying to convince anyone, I am just adding to the conversation. I will likely try it once (after warranty) and see how it goes. Ultimately I don't think running a 10w-30 in hot TX is much different than running a 5w-20 in the cold north, which Fiestas have done for millions and millions miles without issue.
No, you don't have to convince us - you've said it before as well as in our own history - legacy from our own families.

The only thing that has changed is the approach from other oil companies realizing the need for better emissions versus oil breakdown - they too have now turned over to using lighter thinner viscosity oils for the lubrication because the dynamic needs of vehicles to be operated in ANY climate - not just one area of the country where a given viscosity range was considered satisfactory for most driving needs.

IN some instances the extra oil in the gasoline might tend to contaminate a sensor. But if used regularly in correct ratios - the fouling issue isn't the problem. The engine needs to be tended to in some form or another in clearing out the unwanted residue and using such additives aside from all the detergents used with Ethanol (ugh...) the Ethanol itself can add a "sugar" that if not handled and removed (oil changes for example) will turn oil into a corrosive soup that ruins motors - the MMO like any other additive helps coat sooth and relieve an aching motor that eats gas because there is no other way to help thin down the stuck on glue of sugar that Ethanol is part of.
  • The noises a motor makes is not just knock, it is also from sticking and out of tolerance valve train - tapping and excessive effort from the cam to stem effort generates a wear pattern - if the sticky residue of the fuel is not removed the oil itself is on the wrong side of the seal to offset the now sticky valve. Hence the need for the upper valve train lubrication effort to help allow the motor time to help loosen and remove the "dry side" dirt still present in air intake as well as the PCV / EGR mess needed for emissions. Gas blends are supposed to do that for you - but Ethanol is not a lubricant and can build up due to lack of quality or quantity controls at refineries and lack of enforcement at the state regulation level to force gas stations to toe the line and keep providing good quality fuels instead of watered down old and weak volatility stuff suck in a bin that got pumped out last year is now in this years blend mix.
Detergents alone are not the cure all for the motor ailments - although refineries are doing better at the cracking and reforming - the Ethanol roots of it's own origins is / can and will be a problem for all types of motors - including the electric ones that need lubrication and generate heat from the byproducts of the frictions needed to operate and move the vehicle.
 
Last edited:
OP
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Thread Starter #24
Has anyone ever noticed that 5w-30 oil is spec for Fiestas in other countries? I saw a site from Europe (I think) that said that. Can anyone confirm?

I do know that the 2006 Honda Odyssey with the 3.5L V6 I previously owned did call for 5w-30 (instead of 5w-20) all around the globe except for in the USA, due to CAFE requirements.
 

econoboxrocks

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#25
Has anyone ever noticed that 5w-30 oil is spec for Fiestas in other countries? I saw a site from Europe (I think) that said that. Can anyone confirm?

I do know that the 2006 Honda Odyssey with the 3.5L V6 I previously owned did call for 5w-30 (instead of 5w-20) all around the globe except for in the USA, due to CAFE requirements.
Yup. EU Fiestas get 5w-30.
I put 5w-30 in my ST, but I'm going back to 5w-20. Pick up another mpg. I don't stress it enough that it needs thicker oil.
 

Lbrocato

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#26
Yup. EU Fiestas get 5w-30.
I put 5w-30 in my ST, but I'm going back to 5w-20. Pick up another mpg. I don't stress it enough that it needs thicker oil.
I think heavy use get 5w-40 which stop and go traffic not highway speed
 

scotman

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#27
I chose to use 5w30 in my Fiesta ST because I don't have an oil vapor catch can setup that would mitigate a problem with pcv system discharge oil vapors coking on the backside of the valve.
It was a calculated decision to trade one average mpg to potentially eliminate an expensive maintenance issue.
This coming spring I am going to inspect the critical area with an inspection camera and determine whether i should attempt a cleaning, install a catch can setup or ?
The cumulative effect of the oil vapor accumulation on that intake valve is the only reason i went off the reservation regarding oil spec.
 

econoboxrocks

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#28
I chose to use 5w30 in my Fiesta ST because I don't have an oil vapor catch can setup that would mitigate a problem with pcv system discharge oil vapors coking on the backside of the valve.
It was a calculated decision to trade one average mpg to potentially eliminate an expensive maintenance issue.
This coming spring I am going to inspect the critical area with an inspection camera and determine whether i should attempt a cleaning, install a catch can setup or ?
The cumulative effect of the oil vapor accumulation on that intake valve is the only reason i went off the reservation regarding oil spec.
I'm curious to see what you find.
 
OP
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Thread Starter #29
Thanks all. It seems from this that the 1.6 is somewhat tolerant of going up a grade. Good to know.
 
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#31
Has anyone ever noticed that 5w-30 oil is spec for Fiestas in other countries? I saw a site from Europe (I think) that said that. Can anyone confirm?

I do know that the 2006 Honda Odyssey with the 3.5L V6 I previously owned did call for 5w-30 (instead of 5w-20) all around the globe except for in the USA, due to CAFE requirements.
We are the same in Australia.5W-30.
 

scotman

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#32
I'm curious to see what you find.
So am i! What it looks like "in there" will be a big determining factor in my decision to keep it or dump it. My gamble was if shorter drain intervals with high quality synthetic oil of a slightly lighter grade would give me some benefit on the heavy maintenance end of the deal. My question is "if $350 of really good oil and filters were roughly doubled ($700), would i not have to spend that $2,000 in pulling the top end off for a de coking, and valve job? Costs of machine shop labor time have gone up since 2016. So the question is more relevant, to me, now.
 

econoboxrocks

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#33
Thanks all. It seems from this that the 1.6 is somewhat tolerant of going up a grade. Good to know.
If I lived in the southern US, or northern Australia, where temps get to 100+, I'd use 30 weight, and get a mountune radiator.
It's just not an issue where I live. It gets cold, but not real hot.
 

econoboxrocks

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#34
So am i! What it looks like "in there" will be a big determining factor in my decision to keep it or dump it. My gamble was if shorter drain intervals with high quality synthetic oil of a slightly lighter grade would give me some benefit on the heavy maintenance end of the deal. My question is "if $350 of really good oil and filters were roughly doubled ($700), would i not have to spend that $2,000 in pulling the top end off for a de coking, and valve job? Costs of machine shop labor time have gone up since 2016. So the question is more relevant, to me, now.
I haven't read of big problems with that issue. Old Volkswagens, sure, but these are much newer cars. There are tons of FiSTs with high mileage that run fine. Even big turbos cranking 300 hp. The ecoboost is built to take it.
The drivetrain can, too, but it's a wear item when you give it that much power.
Mine's fine. Stock turbo. It's not even working hard at 210/276 wheel.
 
OP
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Thread Starter #35
Revisiting this, I am just about out of warranty, so I am about to try the 10w-30. Temps here are already in the low 90's. Perfect timing with a long hot summer ahead. I will run the 10w-30 for a week or two, observe engine sound, performance and MPG's, then introduce a 1/2 quart of MMO, which will be an 11.6% concentration (0.5 qt. / 4.3 qt.) The MMO directions are to use a 10% -25% concentration in oil, so I am far on the conservative end. All I want the product to do is thin the oil a bit. Gentle internal cleaning is welcome but incidental.
 

LionsTooth

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#36
Revisiting this, I am just about out of warranty, so I am about to try the 10w-30. Temps here are already in the low 90's. Perfect timing with a long hot summer ahead. I will run the 10w-30 for a week or two, observe engine sound, performance and MPG's, then introduce a 1/2 quart of MMO, which will be an 11.6% concentration (0.5 qt. / 4.3 qt.) The MMO directions are to use a 10% -25% concentration in oil, so I am far on the conservative end. All I want the product to do is thin the oil a bit. Gentle internal cleaning is welcome but incidental.
Wait until you smell the MMO out the tailpipe. Yum!
 
OP
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Thread Starter #37
Never used MMO in my 40 years of driving, but I have heard that!
 
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#38
I love MMO. I've regularly run a "purge" of 100% MMO in my 1972 diesel Mercedes and the engine absolutely loves it. After about 2 minutes of running on MMO, the motor will quiet down and sound like a nicely tuned sewing machine.
The recent executive allowance of greater ethanol in our gas has gotten me a little more hypervigilant. I'm on my 4th tank since purchasing the 2016 SE and I've always filled with premium at high-volume gas stations. I noticed on this last fill that the engine is making a few more ticks and possibly a knock here and there; sounds like the valvetrain is slightly noisier. I've added a can of Liquimoly Jectron at the last two tank fillings, but I'm thinking I need a few ounces of MMO. Granted, my hearing is bad and yesterday, when I heard the ticking, I was wearing my hearing aids and standing in the alley next to the house, so the sound was greatly amplified.
I'm just rambling here but also curious regarding oil, fuel, MMO, ethanol...

Phil Forrest
 

LionsTooth

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#39
Just bought a gallon of MMO for oil and gas additions. I used to run it in my Isettas to help lube the valve tappets and it helped with piston ring wear.....not since.
 

scotman

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#40
I also like the fragrance of combusted Marvel mystery oil! I put the stuff in my tractor and mowers when they go into winter storage.
So, it's a sign of spring when i get a whiff of that!
I have used it in my old Mustang before I ran full synthetic oil. I still use it twice a year as a fuel system additive. It never hurt anything to my knowledge.
I wouldn't mix it with a modern semi synthetic oil and then run a 10,000 mile drain interval either.It's not designed for a modern oil change schedule.
My dad always used it in his vehicles as fuel additive or as a motor flush prior to an oil change.
But, he never used synthetic oils. So, his routine was to add a quart of mmo if the oil was down one quart and also due for a change. He would drive the car for around fifty miles or a couple of days and then drain it. He put lots of hard miles on his work vehicles and never had a failed lifter or stuck rings.
Just normal but diligent maintenance.
 


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