Oil viscosity question II

I didn’t want to highjack Tumbleweed’s thread so I will start another.

I hear others recommend substituting 1 quart of MMO along with an oil change if you happen to have a noisy lifter.

I have two questions:

What viscosity is MMO?

What disadvantages/advantages would MMO viscosity have on the engine while interacting with a multi weight oil like 20-50?


My question isn’t what the MMO will do for the engine rather what effect would mixing it with a multi grade oil or for that matter a single grade oil have on the engine.

 

OK, found out the answer to question 1. Anyone know or care to guess?

As for question number two, it depends on who you ask.

"Heavy Duty Oil Stabilizer - Effectively extends engine life by preventing viscosity breakdown, oil thinning, oil consumption, engine wear and oil leaks." MMO

"Marvel Mystery Oil is mostly solvent. You pour it in your crankcase and you get diluted oil. The solvent flashes off at a couple hundred degrees, so it hadn't really done anything."
Howard Fenton, AVweb

"At an FBO I work for, we occasionally use MMO added to the OIL to free sticky valves. Solid stem valves used in Continentals are very prone to carbon and crud buildup on the stems (rarely seen in Lycomings due to sodium filled valve stems). Anecdotal evidence indicates that repeatedly stuck valves often will stay unstuck for a while after MMO use. We don't recommend MMO use in every crankcase refill. We would never use it in the FUEL." Dave

 

MMO is SAE 30 weight.

 

I had used this several years ago to try to quiet the lifters in my '87 Commance 4.0. The mileage on the engine at the time was a little over 100,000. It actually did free up and quiet the lifters.

The engine was leaking oil slightly from the front and rear seals at the time - after adding the MMO both seals had to be replaced as the solvent also removed the build up of sludge around the seals/crank that is normal for a high mileage engine.

 

MMO is SAE 5