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Oil Level

bob888

Well Known Member
Is there a consensus re acceptable oil level to minimize venting through the breather yet maintain a safe margin in the engine?
 
Is there a consensus re acceptable oil level to minimize venting through the breather yet maintain a safe margin in the engine?

6.5-8qts. I know some people who add a half quart or full quart when it gets to there preferred level in this range. Most -10's seem to blow out quickly over 8.5qts.

Edit: ...but I doubt you'll get much consensus on this.
 
Oil level

At oil and filter change I will add 9 qts. of oil. After first engine run that will show at about 8.5 on the dip stick. Fly the airplane until the oil dip stick shows 7.5-8 and then add a quart. (typically 10-15 hrs.) Anything over 9 qts. on the dip stick is too much and will get blow out the breather and show up as on the belly.
I believe the book says the engine will run safely down to something close to 4 qts. but I would not test that....
 
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An O-320 is supposed to have a 2 quart minimum...

Most a/c oil sumps were spec'd to keep from running out of oil before the fuel ran out.
 
I'm curious, have no experience to go on. What is a "normal" hourly oil consumption rate at say half way to OH time? One qt every 5 hours, every 10 hours?
 
oil level

I asked my engine builder years ago, his response- let the oil go down until it stops losing oil. 6qts is were it stops and loses very little below that mark. I have added more (7qts) on new changes and it keeps the same temps and throws it out most oil quickly than stabilizes at 6.
My temps are 200F +/- 10F at 6 qts in warmer climates
 
I'm curious, have no experience to go on. What is a "normal" hourly oil consumption rate at say half way to OH time? One qt every 5 hours, every 10 hours?

I don't think there is a 'normal'. But if you haven't seen the oil consumption numbers that Lyc considers acceptable, you're probably in for a shock. (Hint: oil pan capacity; see my previous post.)

Charlie
 
I'm curious, have no experience to go on. What is a "normal" hourly oil consumption rate at say half way to OH time? One qt every 5 hours, every 10 hours?

The normal/acceptable oil consumption rate is below 5 Hours per quart to upwards of 20.
 
The normal/acceptable oil consumption rate is below 5 Hours per quart to upwards of 20.

More specifically it is given as a maximum in Section 3 of the Lycoming Engine Operating Manual.

It varies by power setting - for a O-360-A model -

Full rating at 2700 rpm - 0.8 qts per hour

Performance cruise (75%) - 0.45 qts per hour

Economy cruise (65%) - 0.39 qts per hour

The economy cruise number would give almost 10 qts used in a 25 hr oil change period. I would be concerned if my engines got close to that..:eek:
 
From Lycoming Service Instruction No. 1427C

From Lycoming Service Instruction No. 1427C

NOTE:
The following formula is used to calculate the maximum allowable oil consumption limits for all Lycoming aircraft engines.
0.006 x BHP x 4 ? 7.4 = Qt./Hr.

For an O/IO-540 260 HP at 75% cruise the limit is .8432 quarts per hour.

TJ
 
From Lycoming Service Instruction No. 1427C

Don't know anyone who would be happy with that kind of oil consumption
but that is what it says in the service manual.
Jesse described a "normal range" for you, mine runs about 14hours per quart.
I guess I am in the normal range.
I would be concerned if all of a sudden my consumption went from current levels to say 5 hours per quart.
 
I asked my engine builder years ago, his response- let the oil go down until it stops losing oil. 6qts is were it stops and loses very little below that mark. I have added more (7qts) on new changes and it keeps the same temps and throws it out most oil quickly than stabilizes at 6.
My temps are 200F +/- 10F at 6 qts in warmer climates
That is my experience and this is what I do...

I put 7 qts in at change time - it registers as 6.5 or so.

At about 40 hours I'll be below 6 qts. If it hits 5.5qts, I add some. Otherwise at 50 hours I change it.

As a by-product, it seems to keep my oil temps above the minimum. I fly out of NC, nuff said.
 
Just another opinion on this subject, but I'll let mine (O-360) burn down to the 5 qt. level, it seems to stabilize there. I won't let it get much lower than that, but I'd be comfortable on a cross country at the level or lower if an oil change is due soon.
It uses ~Qt/15 hrs. so that helps with my comfort doing that.
5qts is well over Lycomings min.
Tim Andres
 
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