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Optimal oil level

bob888

Well Known Member
I'm curious to know what most RV10 owners consider an optimal oil level for their IO540 engines. Mine seems to drift down to about 7 qt fairly quickly after a 9 qt oil change and than remain fairly constant. I worry that may be too low when starting out on a long flight.
 
I don't have experience with a 540, however, most Lycomings quickly blow out oil filled above the optimal level (optimal meaning what the engine likes or will tolerate, not what Lyc recommends) The fact that yours quickly drops to 7 qts and presumably stays there for a while, would indicate that 7 qts should be your max fill. My 320 recommends 8 qts, but any more than 6 gets blown out, so I fill to less than 6 and add a qt when it drops to 4.

What is your oil consumption rate? Your engine will probably run fine on 2 quarts or less (I speculate that you'll still be pumping oil down to one qt, but don't have data to back that up). If you are burning a quart every hour or two, I would be concerned that 7 qts is not enough for a long trip. This is simple math. If you have 7 qts and your minimum is 2 qts (or use Lycomings recommended minimum level, which is 2.75 qts), you can figure out the risk of running low with your current oil consumption rate.

Assuming proper cooling capacity and reasonable blowby/oil consumption, bigger engines don't need more oil than smaller engines. My 496 CI big block holds around 4+ quarts. About the same as the 180 CI in my wife's Honda.

Larry
 
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My O-360 was happiest at 6 qts when the max is 8 so I assumed that 50% more engine would require 50% more oil. You know what they say about assumptions, well, anyway this was wrong.

I was filling my IO-540 to 9qts but quickly found out that it would blow 2 qts out on the belly relatively quickly, even with an antisplat air/oil seperator. I now fill to 7 and add at 6. Mine will go about 13-15 hours before needing a qt at this level.
 
My RV10 is happy running at 6 qts. Checked with Blackstone about this and they said I might see an increase in oil temperature. Haven't noticed this.
 
Our IO390 is happiest with 6 qts on the dipstick. We burn about 1 quart every 25 hours. Oil and filter changes at 50 hour intervals.
 
Our IO390 is happiest with 6 qts on the dipstick. We burn about 1 quart every 25 hours. Oil and filter changes at 50 hour intervals.

That's pretty good! What oil brand/weight are you using? My older 0-360 seems to burn 1 Qt in 12 hrs when using Aeroshell W100plus but 1 qt in 6 hrs when using Aeroshell W80plus.

Bevan
 
Most RV10 owners I know have a similar experience to mine. Fill to seven quarts, and top up at six. Any more and it blows overboard.
 
Interesting. My new thunderbolt is hung but I have not done a first start yet. The dipstick is marked 12QT capacity. Should I only put in 7?
 
not me

For the last 9 years, when I change oil and filter in our RV10, I add 10 quarts which shows as 9 on the dip stick. After 12 hours it will be down to 8 so I add a quart.
 
I have operated 540 Lycomings for 30years. Anything over 9 should be poured on the hangar flooor. Your motor will tell you where it wants to be. I would worry at less than 6 but think many motors like 8-9.
 
In my experience it likes to blow it out at 8 or so. I change the oil and add 7 qts and most of a pint of CamGuard. I add when it gets to 6.5 or so.
 
We have been using Exxon Elite in our last 3 RV's. IO390, O360 and O320. Our 0360 was incredible. Burning 1 guart In 50 hours for over 800 hours. The IO390 is running a close second with 2 quarts in 50 hours with 198 on the Hobbs.
 
Most RV10 owners I know have a similar experience to mine. Fill to seven quarts, and top up at six. Any more and it blows overboard.
Exactly my experience. One quart added at 25-30, change at 50.

After 500 hours I stopped filling to 7, I just put 7 in after a change and add to keep it around 6 on the stick.

No high oil temps even with 5qts in summer.
 
CHT's and oil volume

It's gotten hot again down South and I've been climbing to 6500 plus for the cool air on trips. I run my 0-320 with between 6 and 7 qts. It's just anecdotal and there are many factors, but it seems like my CHT's run about 5 degrees cooler with 7 qts during those long climbs on the 93 degree days we've been having. Does the extra qt make that much difference for others? John
 
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It's gotten hot again down South and I've been climbing to 6500 plus for the cool air on trips. I run my 0-320 with between 6 and 7 qts. It's just anecdotal and there are many factors, but it seems like my CHT's run about 5 degrees cooler with 7 qts during those long climbs on the 93 degree days we've been having. Does the extra qt make that much difference for others? John

It shouldn't make a difference at all, except to take an extra minute or so to warm up with the extra quart. The volume of oil doing the cooling at any given time stays the same even if you change the amount in the sump (at least until you're almost out of oil!). The oil in the sump doesn't do anything to increase heat transfer to the air flowing over your engine.
 
My RV10 is happy running at 6 qts. Checked with Blackstone about this and they said I might see an increase in oil temperature. Haven't noticed this.

I do agree with Blackstone, don?t know what the reason is but I do see a slight increase in oil temp when the oil drops below my preferred 6 to 7 qts
 
Oil consumption RV10

My IO540 has 688 Hobbs and I burn one quart at 10 hours. It blows everything out above 7 quarts. At six, I simply add another about every 10 hours.
 
Oil

My IO540 has 688 Hobbs and I burn one quart at 10 hours. It blows everything out above 7 quarts. At six, I simply add another about every 10 hours.

I have found that mine behaves the same. At oil change I put in 8, which shows about 7 on stick. When it hits 6 on the stick I add a qt which seems about 10-15 hrs so far.
 
I?ve been running down to 6 and 7 quarts the last few months and maybe coincidentally have been noticing oil temps jumping around during cruise from 150, 160 to 200 where I normally try to keep it. My butterfly valve works well and use to control temps by clicking in or out corresponding to a few degrees. It?s been inconsistent lately so doesn?t do it all the time. Wondering if others have experienced that at those levels or I may have a probe problem?
 
Oil Amount

My O540 runs around 10 quarts. I put in 12 at change time. It quickly goes to 11 with some in the filter. Then in 10 hours it will drop to 10 quarts. I tend to put in a quart if it goes below 10, but that's usually at 25 hours then I change it again at about 35 - 50 hours which is a year.

I also have a new IO360. I put in 8. It drops to 7.5 right away due to filter. then down to 7 after a few hours. If it gets to 6 I put in oil. But this is new engine still in break in period.
 
Oil Levels as per Lycoming Operating Manual

When I bought my RV-10 eight or so years ago, the guy that I bought it from gave me a list of things about the airplane that I didn't get a chance to read until after I flew the airplane from Florida to California. The oil stick in the engine has a full mark at 12 quarts but he said "the engine seems to be happy at 6 quarts". I was sure that must be a typo and he really intended to type in 9 quarts which seemed to be more reasonable. Over the years, I have found that I am not burning oil, but blowing it out on the bottom of the aircraft via the breather. Every six months or so I find that I am putting in a lower amount of oil trying to keep it off the bottom of the engine. When I got down to six quarts I was concerned and contacted Lycoming. They told me, what I had already read in the Lycoming Operations Manual for the IO-540, (section 3) the minimum safe oil quantity is 2 3/4 quarts. I have been running at 6 quarts now for about nine months and the engine does indeed seem to be happy there and is blowing far less oil out onto the belly. The temps are still the same and while keeping it topped off at 6 quarts I am adding only a small fraction of a quart every couple of hours. They say that every engine is different but from reading all of the threads posted here, it seems that "less" oil is the most common solution to the oil quantity question.
 
Sorry for the late reply. We have been using Exxon Elite 20W50. I think we will be changing brands soon due to the huge increase in price.
 
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