Oil Usage

[Releew]

I've had the Mooney now for about 2.5 years.  Flown her about ~250 hours.  At first, I was waiting 50 hour cycles to do the regular oil, oil filter, air filter change and clean the plugs and any other normal stuff under the cowl.  Being new to this engine, I started with 15W-50 as recommended by the previous shop.  The engine had a tendency to operate very close to 400F CHT on #3 even on a somewhat cool day.  On a hot day the cowl flaps had to trail slightly open. Other CHT's were in the 375F range.  A senior Mooney flyer/AP/IA told me to switch to 100W+ and it would help with CHT's.  It did help get the CHT's down to a manageable range without having to run with the cowl flaps trailing.   Engine has 1080 Hours on it and compression's are in the mid to high 70's.  I run slightly LOP.

Here is the trend I am seeing.....

• Fill with 7 quarts
• Engine will hold 6.5 quarts for the first ~5 hours of operation
• Slow drop from 6.5 to 6 quarts from ~5-10 hours of operation
• At ~10 hours of operation the engine will not hold anything above 6 quarts
• As time increases, oil usage increases as well, about .25 Quarts per 1 hour of run time

Is this a normal oil usage cycle?  What are you seeing....

Thanks for your input.

Rick

 

 

[M20F]

Good article on the topic. 

http://blog.aopa.org/opinionleaders/2014/07/02/what-makes-an-engine-airworthy/

[carl]

my 66 m20 e likes 5 and 1/2 quarts of 15 -50 on the stick . 

more than that and it just goes  away. when it get to 5 .5 it stays there at about a rate of 1 quart for ten hours . 

carl

[Hank]

I put in 7 qts of 15W-50 every 50 hours, and generally get 12-15 hours on the first quart. Each succeeding quart comes a little faster, the last one does good to last 8. I'll fly local or lunch runs with 5-1/2, but will top off to 6 for a real trip (>2 hours, >8000 msl). I record each quart or half in a little notebook in the plane, along with each flight's tach hours, logged time and destination / purpose. Then I know exactly how often I'm adding oil. It's also a good place to note oil changes, VOR checks, etc.

[Bartman]

Rick,

I have owned and operated my 77 J since 2005 and about 700 hrs and currently about 1400 SMOH with compressions about 70 plus/minus 5.  I see almost the exact same oil consumption as you describe.

I use Aeroshell 15/50, almost always traveling at least 1 hour and up to 4 hour flights, and rarely just around the patch or IFR currency, Full power climbs at 2700 ROM and 2450 RPM cruise at 10-12K and almost always LOP.  I add at 5.5 and shoot for 6 on the dipstick, but 6.5 for longer flights.

I drain and replace the oil only at 25hrs, and change both oil and filter every 50.  I found this improves my oil consumption as the hours accumulate.

[aaronk25]

I run 2700rpm at 8k and above 2600rpm at 6k and 2500rpm at 4K. All at wide open throttle. I full to 7qts on the dipstick after oil change and normally have to add oil at 25 hours when the oil level reaches 5qts.

Most of the time high oil consumption is due to engines that see in frequent use, the cylinder walls rust then the remaining pits quickly wear away the smooth surface rings. Then the higher blow by toasts the cam/lifter faces, it makes metal in the filer and the rest is history.

Really these engines don't care one darn bit if there run at 2200rpm or 2700rpm or on the experimental world greater than 2800rpms.

The cylinders assemblies do care if they are operated in excess off 400 degrees.

I overhauled my 2000 hour cylinders which still met new service limits a at overhaul a year and a half ago. Idle along or run flat out, it doesn't affect longevity ...but let it sit for 60-90 days, especially with older run oil higher in acid count....promotes rust, pits, high oil consumption and cam/lifter failure.

Just my thoughts of the day....

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[Shadrach]

I run 2700rpm at 8k and above 2600rpm at 6k and 2500rpm at 4K. All at wide open throttle. I full to 7qts on the dipstick after oil change and normally have to add oil at 25 hours when the oil level reaches 2qts.

Most of the time high oil consumption is due to engines that see in frequent use, the cylinder walls rust then the remaining pits quickly wear away the smooth surface rings. Then the higher blow by toasts the cam/lifter faces, it makes metal in the filer and the rest is history.

Really these engines don't care one darn bit if there run at 2200rpm or 2700rpm or on the experimental world greater than 2800rpms.

The cylinders assemblies do care if they are operated in excess off 400 degrees.

I overhauled my 2000 hour cylinders which still met new service limits a at overhaul a year and a half ago. Idle along or run flat out, it doesn't affect longevity ...but let it sit for 60-90 days, especially with older run oil higher in acid count....promotes rust, pits, high oil consumption and cam/lifter failure.

Just my thoughts of the day....

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Am I misreading or are you saying that you run your engine until it is down to 2qts in the sump? 

[ArtVandelay]

Am I misreading or are you saying that you run your engine until it is down to 2qts in the sump? 

That's the way I read it too and always at 75% power.

IMHO, that's engine abuse.

[mpg]

That's the way I read it too and always at 75% power.

IMHO, that's engine abuse.

I will go out on a limb and strongly guess that he means that he runs 25 hours,,, then adds just 2 quarts,, 

to again bring it up to 7 qts..

[aaronk25]

Whoops I edited it. Meant to say run it down to 5qts. Then add 2qts. 7 is a bit more than I like to run with and 5 is on the low end, but it doesn't make any difference in engine longevity running at 8,7,6, or 5 qts. It's just about having enough oil on board.

Thanks mpg for the accurately correcting my typo.

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[aaronk25]

I should have added I have a airwolf oil separator so I most likely am recovering more of 1qt above 6qts that normally goes overboard quickly. I don't think the oil separator does much good between 5-6qt range.

I mention this because prior to the oil separator any oil above 6qt line seemed to dump over board quickly.

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