Understanding how oil mixing works

[sangyup81]

Isn't 5w30 a property of oil on the molecular level?

So lets say we're mixing 3 quarts MMO which is 2.6 cSt with 1 quart GC which is 12.1 cSt. (this is all at 100 C) The result is an oil that averages out to 9.725 cSt at 100 C.

Eventually in a long enough OCI, the MMO all evaporates off due to a low flash point.

Do we end up with 3 quarts of GC at 12.1 cSt or with 3 quarts of 9.725 cSt oil?

 

[Gary Allan]

The result should be an oil of about 4.x cSt.

Eventually you would volatilize all of the lighter components of MMO and end up with slightly more than a quart of 12.x+ fluid that may resemble GC. You would also probably have a seized engine.

Now if you've just reversed what you typed and meant 3 quarts of GC and one of MMO ..then your numbers would probably work out.

Again you would probably end up with less than 4 quarts of material with a slightly higher visc depending on what MMO ends up like after all the lighter stuff flashes off.

 

[sangyup81]

whoops, thanks for catching that error
i did mean 3 parts GC and 1 part MMO =X

 

[Colt45ws]

Actually, its probably closer to 8.0, a 20 grade. http://www.rohmax.com/rohmax/en/customerservices/calculationtools/baseoilmixtures/

 

[ARCOgraphite]

Cant really tell what it'll do with all the Vii in the oil. MMO? Is this 1948 and runing SA oils in a flathead? Just last week I put some (3 oz) MMO in my 8hp techumseh snowblower week, since I used 10w30QS, I thought the machine could possibly benefit from a little thinning of the sump a bit. Well, the oil "broke", the engine was rapping like crazy and low on power during snow cleaning in a storm. I had to dump this fresh oil I just put in. All I had left in my outdoor equip stash was 1/2qt 10w30 RT and 1/2 qt mC5K 10w-40. That went in, and thank the heavens the engine is ok. Quiet and torquey and purrs nicely. MMO? Bleechhh!

 

[Zaedock]

Why did you put MMO into an air cooled engine?

 

[hate2work]

Originally Posted By: Zaedock
Why did you put MMO into an air cooled engine?


Why would you put solvent into ANY engine?

 

[GROUCHO MARX]

We refer to it as "blending" in these parts pardner.

 

[Jakegday]

Originally Posted By: sangyup81
Eventually in a long enough OCI, the MMO all evaporates off due to a low flash point.


this would be true if you were running %100 MMO. however when mixed with motor oil, the flashpoint raises considerably

 

[sangyup81]

It must still be under 100 C because I tend to have oil loss equivalent to the amount of MMO I put in whenever I use it in an OCI.

 

[lipadj46]

Originally Posted By: Jakegday
Originally Posted By: sangyup81
Eventually in a long enough OCI, the MMO all evaporates off due to a low flash point.


this would be true if you were running %100 MMO. however when mixed with motor oil, the flashpoint raises considerably


In a mixture the boiling point of each component liquid remains unchanged. I'm not sure what happens to flash point as it is different than the boiling point. But if the mineral spirits will evaporate off faster than the oil ever will.

 

[mechtech2]

I have not noticed more oil use or more blowby in my catch can while using MMO in my crankcase for winter.
[there is more water condensation at times - normal in winter]
I won't use it [MMO in the crankcase] all the time, but it served a winter/cleaning purpose.