Talking about oil "consumption"...my thesis is that 80% of all oil "consumed" in piston GA is actually not consumed, but thrown overboard (due to people filling the oil up way too high usually)...
Yes, good point. My engine is an excellent example. The sump holds 9 quarts but anything above 6 quarts (5 on the dipstick) is thrown overboard. When I perform an oil change, I add 6 quarts and I rarely ever add oil between oil changes (25h).
What is your certified min oil level, Achim?
What is your oil consumption?
My IO540-C4 throws out anything over 10 and the min is 6, so you have 4 usable which is good for about 10hrs, though a marginally airworthy specimen would run for only 1hr!
On topic...Mike Busch.
AFAIK, Lyco specifies a minimum of two quarts for certain engines! (Aircraft manufacturers sometimes specify minimum recommended quantities but that's different story).
That article corresponds to the 12 qts max and 6 qts min for the IO540-C4.
One could fly the engine with just 6 qts in and it would still be OK for the specified range of pitch attitudes.
The problem with that is that if say you are burning 5 qts/hr and you do a 5hr flight, you are now down to 5 which is below the lower limit.
And how far below the lower limit can you go?
Nobody knows.
Obviously it depends on the pitch attitude, so you get this wrong you might unmask the oil pump intake when climbing, which is really handy...
I am sure it isn't 2 qts. Maybe it is 2 qts in an O-200...
No, it really is 2 quarts for certain O-360 models. Not sayin' it is wise to do that. See here.
BTW, the O-200 is a Conti...;-)
What is your certified min oil level, Achim? .. I am sure it isn't 2 qts. Maybe it is 2 qts in an O-200...
Sump capacity 8qt, total capacity 9qt. The TCDS says minimum safe oil quantity for 20° nose up or down 2.75qt and for 30° nose up 2qt.
So I'm fine with 6q in the system. There is no use in having the system overflow. Look at all those rental aircraft where clueless people keep on adding oil which leaves the system right away.
The TCDS of the IO-540-C4D5D (TB20) doesn't give a minimum oil quantity but the TB20 TCDS does: 6qt. That is a lot and probably not based on actual necessity. I assume Socata didn't have guidance from Lycoming and not knowing much about this while not wanting to take risk, chose a safe high number.
What is your oil consumption?
Negligible. My oil change interval is 25h and I don't add oil in between. Will see how that goes with the freshly honed cylinder #5. If you know your engine well there is no reason to try to keep a lot of oil in the system.
If your oil usage is less than 1qt in 25hrs, that is a miracle engine.
I have never come across any "540" style engine burning less than 1qt in 10hrs.
The TCDS says minimum safe oil quantity for 20° nose up or down 2.75qt and for 30° nose up 2qt.
Isn't that the other way round?
If you can go from 6 down to 2, that is comparable to mine which goes from 10 down to 6.
Since I'll be getting my zero-timed IO360 back in the next week or so I shall be utilising the information in this thread and reporting back.
The TCDS says minimum safe oil quantity for 20° nose up or down 2.75qt and for 30° nose up 2qt.
Isn't that the other way round?
I thought so, too but check here, page 3. Note the "nose up or down" vs "nose up".
If you can go from 6 down to 2, that is comparable to mine which goes from 10 down to 6.
Yes but I still think there is no technical reason for yours having to carry 6qt. It's pretty much the same engine with probably the difference that Socata used an existing engine and did everything on their own and wanted to be absolutely safe whereas in my case it was a joint engineering project where Lycoming created the engine variant for this specific application. Cessna had trouble fitting the retractable nose gear and went from Conti to this specific Lyco to make it work. Therefore they went for a rather small oil sump and Lyco allowed it in their TCDS.
A Lyco rep (actually rather knowledgable, he did inflight shutdown investigations for years) at Aero told me the engines are generally fine on 2qt but one wouldn't want to get near that of course. FAA requires at least 2x the actual minimum for certification.
