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Excessive Oil Consumption

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Disclaimer: These IAC pages are developed by individual IAC members and do not represent official IAC policy or opinion.

Collected by: Charles Chadwick



I have an S2A and it seems to push quite a bit of oil out the breather when I'm doing any kind of inverted work. I'd guess a half pint to a pint in a half hour flight. On occassion the breather will get so hot from the oil you will burn your arm on the pipe in the cockpit. Any comments?

From: Charles Chadwick <>


From: "Bert H. Berrong" <>

Seems to me you are lucky and cheap. I use a quart every flight when I do the unlimited known or free. Fair amount of outside and plain inverted stuff. Worst is the rollers. I usually figure $0.5 per roll, thus a four turn roller is half a quart. This oil dumping is also quite sensitive to how much oil you have to start with and how tall is the stand-pipe (bottom of engine) or going up into the oilpan.

Bert Berrong Brighton, Colorado

From: Gil Tellier <>

I get 8 hours to a quart of straight 50 weight Aeroshell oil in a S-1S with 270 hours since new on a stock 180 hp Lyc with Air Wolf filter, B&C vacuum pad adapter return, no oil screen and a thermostatic valve. Of the 8 hours, about 5 hours are Intermediate akro with lots of snaps. Upright to inverted results in only a slight and momentary drop in oil pressure that normally runs between 75 and 80 psig via EI digital gage. Oil temp runs nominally about 180F with cyl temp of about 350-375F. Oil temp on the hottest day at Santa Paula, CA this summer reached 208F after 45 minutes of continuous akro. Your oil consumption sounds excessive and is certainly more than I observed with my S Decathlon over 8 years of Sportsman akro and 1100 hours with the same model engine as above, except for the filter and vac pad adapter. The adapter significantly reduced oil pressure drop in rolls. I use AOA for oil samples via Aircraft Spruce. Not scientific data but hope it helps.

In my previous post I forgot to add that I maintain my oil between 6 and 6 1/2 qts. As Steve notes, a higher level will result in greater consumption. Gil

Gil Tellier, IAC Ch 49

From: Kent Taylor <>

For what it's worth ... I have a 1978 factory-built S1S (the one that starred in 'Cloud Dancer) with a stock 180 hp AEIO360-B4A, about 800 hrs TTSN. I typically practice an hour at a time, Sportsman and Intermediate maneuvers. Oil pressure is 80 psi upright, 75 psi inverted with a VERY brief blip down to 65 psi during the transition. The only thing that comes out of the breather is water vapor. The engine consumes about 1/2 quart of oil between changes (15 hours).

CAVEAT: My home field is at 7,000' MSL, and the top of my practice box is 10,500' so at best I'm only generating 70% power. However, I haven't noticed any significant differences at sea-level contests.

I agree with keeping the oil at around 6 Qts. I'm using 2 Qts in 20 hrs with full time acro,(6+,2.5-). I also have IO360-B4A with 660 hrs. However I am flying between sea level and 5000 ft.

Kent Taylor Pres IAC Chapter 12 (Rocky Mtn Aerobatic Club)

From: "Mark Sandorf" <>

My Extra 300L loses at least that much when doing heavy inverted work. The guys at Lycoming (IO-540) say that it is perfectly normal. I just keep a coffee can under the breather tube in the hangar...The main thing to watch out for is to make sure the oil pressure doesn't drop to unacceptable levels while inverted. Add it to your pre-acro checklist the first time you roll inverted each day!!!

From: "Mark Stuart" <>

WOW! I'd be happy with your oil consumption ! The S1S that I now fly, and the one I used to own had me putting in a quart every 1/2 hour or so (2 flights). Mind you, on cross countries I could go 8 hrs to a quart. Consumption seems to depend largely on the types of acro you are doing. I know those guys with the 'big' engines can dump out 3 quarts in one flight! Biggest oil eaters appear to be rolling circles, or anything that has you going pos/neg frequently especially with lateral loads. Every time that ball flops, you lose a bit of oil. In practising competition sequences, you should not loose a whole lot until advanced or unlimited. Airshow flying is totally different because you are doing things that LOOK out of control, and crazy. Tumbles, lomcevaks, multiple ratcheting rolls, rolling circles, etc. Mondo oil gobblers. My best advice is that if you are concerned about how much oil ($) is going out the tail, buy stock in Aeroshell !!!!!!!!!!!!

Have fun !!! !!!! !!!!!

Mark Stuart


just a few comments on excessive oil use.. my s1s with a pumped io-360 (straight valve) used a lot of oil, almost all drained out of the eng breather. about a qt every 6-8 hrs when doing adv unl aerobatics. tried synthetic oil but it got too expensive. now i have an aircraft with an aeio-540 (260) and it seems to make oil. fill it to 12 qts and seldom add any more between oil changes, 20-25 hrs flown between changes. opinion only... but i've found aeroshell 100 the best, frequent oil and filter changes are the secret. we buy aeroshell for about 16 bucks a case at the local discount house,

cheap insurance.


From: (Rob Jacobsen)

Your oil consumption during inverted flight sounds pretty normal to me. Right in line with what my S1E consumes. Oil loss during inverted flight is a perfectially normal characteristic of the Christen system and has nothing to do with the state of the engine. The oil analysis you seek will tell you about metal in the oil (for example a bearing going south), but nothing about the state of the inverted oil system. If anything is not quiet right it will be that the ball valve in the seperation canister is not seating correctly - clean it. The Lycoming manual gives directions on how to do this.

From: "Ron Saglimbene" <>

You probably are blowing off that much oil because you're putting too much into the engine! Try this- put in 8 quarts & go fly. When you return, the oil level will be down to 7 or maybe 61/2 quarts. I bet if you go fly again, the oil level will not drop that much, You will eventually reach a level where you will stop blowing off the excess. It might be at only six quarts in your engine. THAT'S WHERE YOU FILL IT TO- NO MORE! Otherwise you're just pissing it away. The Lyc in my "T" would run at six quarts . My S2S is supposed to take 12 Quarts, but anything more than 9 will be blown out. See you in L.I.

Ron Sag


That's normal. I'd start worrying if it did not spit oil.

From: "Cummings, Steve - TP1SMC" <>

Another comment...

My experience (corroborated in discussions with numerous others) is that if you try to keep your sump full, you will dump lots of oil. If I top off my sump (Pitts S1-S w/ IO-360) at 8 quarts, I will dump nearly a full quart on the first flight (doing advanced sequences). If I just let it go, it seems to stabilize around 6-1/2 to 7 quarts. When it gets to 6-1/2, I add about 1/2 quart. Uses a lot less oil this way.

Steve Cummings Corona, CA


If you're only using 1/2 quart in 15 hours, I think maybe you're not having enough fun.

Doug Sowder

From: Kent Taylor <>

I don't know if it would be legal to have any more fun than I've been having!

The more I think about it though, the more I suspect my low oil usage is a function of altitude ... 10,000 ft, full throttle is just about 65% power. And it's generally pretty cool up there, too; oil temp rarely gets much over 180.

From: Mike Maloney <>

My S2A will dump oil out the breather in proportion to the type of flying I'm doing... Pull/push hard more oil. I do not get a pint or even close to that however. Also, I have not noticed heat from the breather tube although the next time I fly I'll check.

Also, my plane will throw out any oil over about 7 quarts very quickly... then it settles down. After an oil change I will have larger puddles on the ramp.

Mike Maloney Chapter One Newsletter editor Pitts S2A N80031

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