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Thread: Best Practices for Reducing Oil Consumption

  1. #31
    Gilbert Pierce's Avatar
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    Default Re: Best Practices for Reducing Oil Consumption

    The pictures the OP posted of the belly were not consistent, in my opinion, with oil being sucked out of the crankcase breather.

  2. #32
    akflyer's Avatar
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    Default Re: Best Practices for Reducing Oil Consumption

    Quote Originally Posted by Gilbert Pierce View Post
    The pictures the OP posted of the belly were not consistent, in my opinion, with oil being sucked out of the crankcase breather.
    There is evidence of oil, not as much as he is loosing, but there is oil on the belly. At any rate, why not take care of simple things while working this out?

  3. #33
    Subsonic's Avatar
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    Default Re: Best Practices for Reducing Oil Consumption

    Quote Originally Posted by Gilbert Pierce View Post
    I replaced all four cylinders with new steel cylinders, ECI/Continental. I am averaging 11 to 12 hours per quart. I run the engine hard, cruise at 2500 to 2600 rpm.
    So, here's where I get in trouble with my dumbass comments. Just shoot me.

    First, if you're coking your oil rings its a sign of over heating the oil. That can be caused by a lack of oil, allowing the available oil to (locally - around the oil scraper rings) boil off the lubricant and leave the carbon, which causes the rings to stick.

    My opinion: The aircooled aircraft engines (O-320) were designed to throw oil overboard. You're not supposed to save oil. You are supposed to fill it up to 8qts and when it gets to 7, you add a qt. If it gets to 6 you add 2 qts. They don't put this in the manual. You're supposed to figure it out. That's why the dipstick says 8 at the top.

    All of you that think you've figured out your oil usage rates by running your crankcases half full are on your way to a rebuilt $35K engine. Or, $55K new. Or new jugs every 600 hours or so...Again, it's my opinion.

    Oil is lubricant and coolant.

    Also: I know this. Lycoming "LIES" (or, should I say they have their engineering opinion) about their acceptable head temps.

    My opinion: Just because they can run an engine for 5 or 6 months and 1000 hours on a test stand at those temps doesn't characterize the use/aging of a 20 year old engine in a normal airplane. Aluminum is always decomposing. Same with iron. They're different, but not so much. They both oxidize, and lose strength through that process. It leads to micro-cracking, and it grows. Thermal cycling accelerates it. Higher amplitude swings in temp accelerate it more.

    Where I come from, NO aerospace engineer likes aluminum above 300 degrees F. It loses too much strength. 350 deg. is doing damage. 400F is DESTROYING the aluminum. Quickly. It's oxidizing and decomposing, and cycling up and down to these temps is just pure destruction. It takes time, but it is becoming more brittle and micro-cracks are developing...look at the strength of alu. vs. temp. curves that you can google up everywhere. Cycling those over time just kills aluminum.

    I try to keep my CHT's to 340 or less on my O-320. Still too high. Car engineers figured it out 25 or 35 years ago. They run unleaded fuel and synthetic oil. Their engines have doubled and tripled their lifespans in that period. And they manage their temps better. Luxury of liquid cooling.

    So, I run both aviation approved (Cam Guard and AvBlend) oil additives in my Aeroshell 100plus. Now I think I'd like a remote reservoir/sump. Or, just keep adding a quart every two or three hours. Probably the latter.

    Comments appreciated.
    Last edited by Subsonic; 02-13-2024 at 01:05 AM.

  4. #34
    Administrator Steve Pierce's Avatar
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    Default Re: Best Practices for Reducing Oil Consumption

    New manufacture cylinders will get low oil consumption. Better manufacturing process, rounder cylinders. I have noticed they break right in as well. Lycoming publishes a minimum oil amount for each engine. It is rather low. The issue is the oil transfer heat and the lower oil level can raise the oil temp to an unacceptable level. There is very good guidance from Lycoming but also a lot of variables. The issue with the O-290 is twofold, older cylinders with nothing new available and a limited crankcase vent design for the engine. I dislike rebuild cylinders for the reasons posted above, hot and cold cycles are hard on heads. I have pulled too many cylinders for cracked heads. Some with a few hundred hours since overhaul but some make it to tbo. It is a crap shoot. The only new cylinders I have pulled were for stuck valves.

  5. #35
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    Default Re: Best Practices for Reducing Oil Consumption

    Quote Originally Posted by ghostofme View Post
    It consumes around a quart of oil every 2 hours, which seems like a lot from my very basic understanding and research I've done. Is this normal? I may as well buy the 55 gallon barrel advertised on websites two times over! I'm currently running Aeroshell Aviation Oil W100+ and flying around 4 times a week, 5 hours per day. I'd appreciate any feedback. Thanks!
    Lycoming Service Instruction SI 1427 Identifies using the Lycoming Operators manual for your specific to engine to determine oil consumption. The attached documents list the highest oil consumption for the D2 as .60 qts "MAX" at high rpm an hour. It proves in my mind that the 290s are different animals. The 290 uses a wedge piston ring. That is the combustion pressure above the ring pushes it outwards against the cylinder wall. Look at #4 for the cause of "excessive oil consumption" incorrect installation of piston rings. If the rings are installed upside down they won't last too long. Explains the "probable cause", worn piston rings. Install new rings, part numbers up.

    I have a digital 290 operators manual if you need it.
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    Last edited by Vagabondblues; 02-13-2024 at 10:10 AM.

  6. #36

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    Default Re: Best Practices for Reducing Oil Consumption

    I've never had an issue running an engine with oil levels at the level they stabilize at, often somewhere between 6.5 and 5 quarts. Once you find that level, just keep it there. I have run O-320 engines as long as 7000 hours between overhaul with no issues. The one that ran 7000 hours still had the same cylinders on it and was used for glider tow exclusively. I've run banner tow engines well in excess of 3000 hours with no issues either. Almost any engine with full oil (Lycoming or Continental) will kick the top quart out within a couple hours. Some the top couple quarts. My IO-320s on my PA-30 like to run at 6 qts and these engines sat for 24 years before I started flying it last spring. The key to running these engines is run them hard, pay attention to your baffles, and lean appropriately to keep the carbon and lead out of your oil.

  7. #37

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    Default Re: Best Practices for Reducing Oil Consumption

    Quote Originally Posted by Subsonic View Post
    So, here's where I get in trouble with my dumbass comments. Just shoot me.

    First, if you're coking your oil rings its a sign of over heating the oil. That can be caused by a lack of oil, allowing the available oil to (locally - around the oil scraper rings) boil off the lubricant and leave the carbon, which causes the rings to stick.

    My opinion: The aircooled aircraft engines (O-320) were designed to throw oil overboard. You're not supposed to save oil. You are supposed to fill it up to 8qts and when it gets to 7, you add a qt. If it gets to 6 you add 2 qts. They don't put this in the manual. You're supposed to figure it out. That's why the dipstick says 8 at the top.

    All of you that think you've figured out your oil usage rates by running your crankcases half full are on your way to a rebuilt $35K engine. Or, $55K new. Or new jugs every 600 hours or so...Again, it's my opinion.

    Oil is lubricant and coolant.

    Also: I know this. Lycoming "LIES" (or, should I say they have their engineering opinion) about their acceptable head temps.

    My opinion: Just because they can run an engine for 5 or 6 months and 1000 hours on a test stand at those temps doesn't characterize the use/aging of a 20 year old engine in a normal airplane. Aluminum is always decomposing. Same with iron. They're different, but not so much. They both oxidize, and lose strength through that process. It leads to micro-cracking, and it grows. Thermal cycling accelerates it. Higher amplitude swings in temp accelerate it more.

    Where I come from, NO aerospace engineer likes aluminum above 300 degrees F. It loses too much strength. 350 deg. is doing damage. 400F is DESTROYING the aluminum. Quickly. It's oxidizing and decomposing, and cycling up and down to these temps is just pure destruction. It takes time, but it is becoming more brittle and micro-cracks are developing...look at the strength of alu. vs. temp. curves that you can google up everywhere. Cycling those over time just kills aluminum.

    I try to keep my CHT's to 340 or less on my O-320. Still too high. Car engineers figured it out 25 or 35 years ago. They run unleaded fuel and synthetic oil. Their engines have doubled and tripled their lifespans in that period. And they manage their temps better. Luxury of liquid cooling.

    So, I run both aviation approved (Cam Guard and AvBlend) oil additives in my Aeroshell 100plus. Now I think I'd like a remote reservoir/sump. Or, just keep adding a quart every two or three hours. Probably the latter.

    Comments appreciated.
    Max sump oil level is connected to max fuel onboard when aircraft are certified. The goal is to run out of fuel before you run out of oil. Engines are not designed to throw oil overboard it was just the nature of the beast. If I remember this all right the OP has a high time motor and is running 100 LL with 50 hour oil changes. You would expect a lot of blow by that is contaminating the oil and sludge/carbon buildup in the rings causing problems. Very good chance he has a broken ring two but have to wait to see what inspection shows. Like I posted earlier a cylinder flush and 25 hour oil changes may be the cure but I would not bet money on it. I do agree that Lycomings CHT numbers are way out of line but lately they have backed down to recommend lower numbers for prolonged operation. I did press a rep several years back asking if they really ran a engine at 500 degree CHT for 2,000 hours and he said no they would only hit the temp and then back down below 400. They had to come out with the wet head cylinder to keep from burning up exhaust valve guides on one model. I also like to keep my CHTs in the 300-340 range if possible.
    DENNY

  8. #38
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    Default Re: Best Practices for Reducing Oil Consumption

    Agree and experience every thing above. I have also always run my "320's" hard.
    "Progress is our most important problem"

  9. #39

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    Default Re: Best Practices for Reducing Oil Consumption

    Quote Originally Posted by PACERGUY View Post
    Max sump oil level is connected to max fuel onboard when aircraft are certified. The goal is to run out of fuel before you run out of oil. Engines are not designed to throw oil overboard it was just the nature of the beast. If I remember this all right the OP has a high time motor and is running 100 LL with 50 hour oil changes. You would expect a lot of blow by that is contaminating the oil and sludge/carbon buildup in the rings causing problems. Very good chance he has a broken ring two but have to wait to see what inspection shows. Like I posted earlier a cylinder flush and 25 hour oil changes may be the cure but I would not bet money on it. I do agree that Lycomings CHT numbers are way out of line but lately they have backed down to recommend lower numbers for prolonged operation. I did press a rep several years back asking if they really ran a engine at 500 degree CHT for 2,000 hours and he said no they would only hit the temp and then back down below 400. They had to come out with the wet head cylinder to keep from burning up exhaust valve guides on one model. I also like to keep my CHTs in the 300-340 range if possible.
    DENNY
    and the CAR 4 oil quantity requirement of 1 gallon of oil for each 20 gallons of fuel is based on radial engine oil consumption.

  10. #40

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    Default Re: Best Practices for Reducing Oil Consumption

    [QUOTE=Subsonic;146847]So, here's where I get in trouble with my dumbass comments. Just shoot me.



    My opinion: The aircooled aircraft engines (O-320) were designed to throw oil overboard. You're not supposed to save oil. You are supposed to fill it up to 8qts and when it gets to 7, you add a qt. If it gets to 6 you add 2 qts. They don't put this in the manual. You're supposed to figure it out. That's why the dipstick says 8 at the top.







    Why would they design it to throw oil overboard??

    Rick

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