Does MMO burn off in the crankcase?

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Nov 17, 2019
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Alberta
I put about 500ml of MMO in my 5qt engine. Runs fine.

Before filling I replaced my oil pan gasket. I've since lost about 1/2 litre according to the dipstick. 800 kms driven. No oil below. This van has never burned oil either.

I'm thinking it's the Marvel Mystery Oil burning off. I thought I read that can be expected but can't find any confirmation.
 
Originally Posted by blufeb95
It's mostly a bunch of solvents, so yes it will evaporate out of the oil like fuel does will when the oil is up to temp.



that's great. TY.
 
Yes exactly. The solvents can burn off, which is why putting MMO in the crank for a little cleaning near the end of an OCI can still be effective. It does most of it's cleaning early after it's added. Nothing wrong with putting it in when you change the oil either, however it is wise to account for the thinning it will create.
 
Originally Posted by 2009Caraman
I put about 500ml of MMO in my 5qt engine. Runs fine.

Before filling I replaced my oil pan gasket. I've since lost about 1/2 litre according to the dipstick. 800 kms driven. No oil below. This van has never burned oil either.

I'm thinking it's the Marvel Mystery Oil burning off. I thought I read that can be expected but can't find any confirmation.

It's not going to burn off, it's not moisture, just dillutes the oil. Beginings of oil usage is one reason I do not add cleaning solvents to my oil. A buddy of mine seized up his engine when he added kerosene to his oil. It cleaned too good, loosened up some sludge which plugged an oil gallery feeding the bearings.
 
Last edited:
Originally Posted by Lubener
Originally Posted by 2009Caraman
I put about 500ml of MMO in my 5qt engine. Runs fine.

Before filling I replaced my oil pan gasket. I've since lost about 1/2 litre according to the dipstick. 800 kms driven. No oil below. This van has never burned oil either.

I'm thinking it's the Marvel Mystery Oil burning off. I thought I read that can be expected but can't find any confirmation.

It's not going to burn off, it's not moisture, just dillutes the oil. Beginings of oil usage is one reason I do not add cleaning solvents to my oil. A buddy of mine seized up his engine when he added kerosene to his oil. It cleaned too good, loosened up some sludge which plugged an oil gallery feeding the bearings.

It's mostly napthenic solvent and mineral spirits which are pretty volatile and when the oil is up to temp should readily evaporate into the crankcase and get sucked up into the intake through the PCV and burned off
 
Originally Posted by blufeb95
Originally Posted by Lubener
Originally Posted by 2009Caraman
I put about 500ml of MMO in my 5qt engine. Runs fine.

Before filling I replaced my oil pan gasket. I've since lost about 1/2 litre according to the dipstick. 800 kms driven. No oil below. This van has never burned oil either.

I'm thinking it's the Marvel Mystery Oil burning off. I thought I read that can be expected but can't find any confirmation.

It's not going to burn off, it's not moisture, just dillutes the oil. Beginings of oil usage is one reason I do not add cleaning solvents to my oil. A buddy of mine seized up his engine when he added kerosene to his oil. It cleaned too good, loosened up some sludge which plugged an oil gallery feeding the bearings.

It's mostly napthenic solvent and mineral spirits which are pretty volatile and when the oil is up to temp should readily evaporate into the crankcase and get sucked up into the intake through the PCV and burned off


Hmmm, wonder if that could possibly clean the intake valves on GDI engines???
 
Originally Posted by Drew99GT


Hmmm, wonder if that could possibly clean the intake valves on GDI engines???

I Doubt it, probably not much different than the normal amount of fuel that travels through the PCV from blow by and fuel contamination.
 
Originally Posted by Lubener

It's not going to burn off, it's not moisture, just dillutes the oil. Beginings of oil usage is one reason I do not add cleaning solvents to my oil. A buddy of mine seized up his engine when he added kerosene to his oil. It cleaned too good, loosened up some sludge which plugged an oil gallery feeding the bearings.


Not a Chemical Engineer or Chemist but this is what my own experience has shown and OA reflects. Once its blended its bonded and there for the duration.
 
Originally Posted by blufeb95
Originally Posted by Drew99GT


Hmmm, wonder if that could possibly clean the intake valves on GDI engines???

I Doubt it, probably not much different than the normal amount of fuel that travels through the PCV from blow by and fuel contamination.


They used to make "top end oilers" that would deliver a small amount of oil into the intake to act as a UCL.
I've been wondering if that sort of system wouldn't work with the right fluid (Seafoam, MMO, etc.) To keep the intake and valves clean on engines that suffer from this problem (VW TDI, most GDI engines).
 
Originally Posted by ABN_CBT_ENGR
Originally Posted by Lubener

It's not going to burn off, it's not moisture, just dillutes the oil. Beginings of oil usage is one reason I do not add cleaning solvents to my oil. A buddy of mine seized up his engine when he added kerosene to his oil. It cleaned too good, loosened up some sludge which plugged an oil gallery feeding the bearings.


Not a Chemical Engineer or Chemist but this is what my own experience has shown and OA reflects. Once its blended its bonded and there for the duration.


My experience backs this up that it would likely NOT evaporate out. I have put like 40% MMO in engines (cleaning was needed) and after about 1000 miles most of it was still there.

On extremely dirty engines, monitor oil level, yes... but MMO is not the strongest.

Would Seafoam evaporate...
 
Originally Posted by Lubener

It's not going to burn off, it's not moisture, just dillutes the oil. Beginings of oil usage is one reason I do not add cleaning solvents to my oil. A buddy of mine seized up his engine when he added kerosene to his oil. It cleaned too good, loosened up some sludge which plugged an oil gallery feeding the bearings.


Not a Chemical Engineer or Chemist but this is what my own experience has shown and OA reflects. Once its blended its bonded and there for the duration.

I have a quart in my GM 5.3L engine and a quart in my friends VW 2.5L engine. Been about 1000-2000 miles on both motors, so far has not burned off. It 100% diluted the viscosity since MMO is about a straight 5w
 
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