Air-Oil Separators

[alehmann]

My Continental O-470R with all chromed cylinders is reluctant to keep the crankcase oil too long.  I am getting tired of buying aviation oil boxes at a time.  Someone suggested making my own air-oil separator.  The commercial models tracked down so far are: Andair (UK), M-20 (USA), Airwolf (USA).  The last two seem to be waging a war against each other on their homepage links, making it difficult to decide who is right or wrong. So all experiences with air-oil separators are welcome.

[Snowflake]

Just a thought, but how much oil do you try to keep in the engine from day to day?

My O-320 seems to stay quite happily at 5.5 on the stick (which is marked up to 8 ), and if I add any more it tends to ooze it out over time.  For an oil changes now I fill to 6 and let it settle back to 5.5.  I only add if it gets to 5.  If you're trying to keep it "full" that may be the majority of your problem.

Lycoming says my O-320 will safely run with oil as low as 2 (!!!) so there's still a good buffer there.

[alehmann]

My airplane engine-overhaul shop owner suggested flying my 230 hp Continental on as low as 5 qts if necessary to see if it will stabilize its oil elimination.  He also agreed that with chromed cylinders that may have reached middle age, new rings have a difficult time in seating.  Another point he raised is oil viscosity; he suggested I use the correct single viscosity oil according to the season instead of multi viscosity oil I used.  An oil/air separator should be the best solution for my engine he claims, and just now I finished the installation of an Airwolf oil/air separator.  I will monitor its efficiency on our trip to Oshkosh next week, and will post my findings upon return in August.

[alehmann]

Here is what I experienced during my flight to and from Oshkosh:  I tried to keep the oil level at 7, and during the whole trip to Oshkosh I was down one quart by the time reaching it, and similarly on our return.  By following the advice of my a/c engine overhaul expert, and the air-oil separator, I reduced the consumption of oil by 50%.
 

[irishfield]

Please tell me you're not running that Aeroshell 15W50 crap.... and if you are.. switch to either Aeroshell 100 or Phillips 20W50 and you'll see your consumption return to normal. I swear AME's get people to switch to the 15w50 just so they can sell them a top overhaul , when all they need to do is switch back.

[Snowflake]

Hmm... I'd like more info, Irishfield.  Unless i'm mistaken, the Phillips oil doesn't have the Lycoming additive for anti-wear on the cam lobes, so it's a non-starter for me.  I'm open to reasons to switch to W100, if they are founded on some kind of reality and not old wive's tales.

What about the 15W50 makes it "crap"?  I've gone the last 25 hours without adding *any* oil, running 15W50, and leaving it at 5.5 on the stick.  And that's on a Lycoming with almost 4000 hours on the clock, and just over 2000 SMOH.