Thanks for the break and the info Jeff! So are you saying that it is gas being added to the crankcase oil that makes the level rise? Or is it that the oil and MMO (and gas, in a rich or flooded engine) recovered from the combustion chamber is being recycled back to the crankcase, causing dilution of the oil with unburned gas and anything that has been added to it?

Thanks!
Ray

 

WTF! are you guys talking about ? Thats Ubsurd gas is not injected into the crank case, Rotarys consume OIL!
If this is some kind of a joke and Im not getting it Im sorry, but sounds to me you guys are way off track.

 

Hmmm. That's interesting: gas in the crankcase oil. I tend to replace oil filters a couple times between oil changes, figuring that oil doesn't deteriorate, just gets dirty from the detergent, so it needs to be cleaned. Back in grad school I had a 48 Austin A40 that used oil badly, so I bought recycled oil that had been put thru an activated charcoal filter: worked fine. Smelled and felt right, too.

But filters won't remove gas. On the other hand, I have NO flooding problems.

B

 

No Joke Jimmdog, just trying to figure out how the MMO and, in flooded engines, the gas gets into the engine oil. Anybody know?

 

it's gotta be a Marvelous Miracle of some sort

 

I think it has something to do with the way the oil seal rings are beveled, but I'm really not sure.

True is though, that gas (and anything carried with it) does get into the crank case in small quantities. Gas is light, and evaporates easily, so once the engine is warm most of it is quickly removed by the crankcase ventilation system. MMO because it doesn't evaporate as easily would be left in the crankcase.

 

OK, I was getting the impression somebody was thinking fuel was Purposely injected into the crank case. I did'nt want some nieave Noob to think fuel mix in the oil might be a cool performance mod. LOL

 

What about fuel vapors getting into the crankcase via the hose connections on the oil filler tube?

 

Since I still use an OMP, I never worry about the oil level going up.

Wankelguy, if the PCV valve is working right, any fuel vapors would end up getting sucked into the manifold and burned along with the incoming air. If it's not functioning correctly, there will be a slurry of wonderfulness under the oil filler cap (but you already knew that).

Hey ray green, if you ever get the chance to tear down a 12A or whatever, you'll see that there is no way that gas will ever get added into the oil system. It still gets in though through normal engine opperation. Just ask peejay. There's also a little water in the mix, although a very minute amount.

There is no recycling going on. Most of what's in the rotor housings gets pushed out through the exhaust ports. Only a fraction gets past the oil seals.

Ever smell your dipstick? Tell me what it smells like.

 

Thanks for the explanation Jeff, so there's no oil return system in the rotary, however a small amount of combustion liquids (oil, gas, whatever else gets in there and isn't quickly combusted) can leak by and get in the engine oil. I suppose the more oil you put in the gas, the more oil gets into the engine, especially older ones with leakier seals. Thus this "replenishment" can account for the apparent reduction in oil consumption I've discovered since I started adding MMO to the fuel.

This explanation is consistent with a calculation I did last night using the Haine's manual, which says that the OMP delivers about 2 cc (or ml, for us scientists) of oil to the carb per minute at 2000 rpm. Double this for the 4000 rpm I usually cruise at for 2 hours each day and you find that 2 ml x 2 x 10 hours = 40 ml oil consumed each week for about 500 miles of driving. Now multiply by 6 to get the 3000 miles between oil changes and you have 240 ml of oil consumed between changes, or about a third of a quart, probably not enough to notice, assuming there is no other significant consumption of the engine oil.

So in my case I can explain the fact that my engine oil level stays the same between oil changes by the small but normal consumption of the engine oil by the OMP being compensated somewhat by the "leaking" oil from the combustion chamber. The amount of oil (and MMO) "leaking" from the combustion chamber has probably increased a bit since I started adding MMO to the fuel, which is what got me wondering about this.
Another MMO mystery solved, thanks guys!

Ray