Hi everyone.
I have a new Lycoming IO-540 in an RV-10 that I've been running mineral oil in as per recommendations. Lycoming suggests mineral oil for the first 50 hours or until "oil consumption has stabilized". I'm not sure about the oil consumption stabilizing - it seems to go through about a half a quart in 8-10 hours, as it has since the beginning... but even with that, much of that could just be being blown through the breather tube (I have yet to find the perfect "sweet spot" in filling the oil where the sump is as full as it can be without just tossing excess overboard).
In any case, with the lack of knowing if the oil consumption has "stabilized" or not, I figured I'd just run mineral oil for 50 hours and then change it out for ashless dispersant.
The trouble is, I'm planning on being away from base on a fairly long trip when the 50 hour mark hits.
I last changed the oil (for mineral oil again) at 25 hours and am currently at 35 hours. I'll likely be at around 40 hours when I do the trip, which I expect will put about 20 hours on the engine.
So, would people recommend that I change the mineral oil for ashless dispersant at 40 hours, right before I leave? Or would it be better to leave mineral oil in until around the 60 hour mark, when I get back? In other words, is it better to run mineral oil for a little longer when the engine is ready for ashless dispersant, or switch to ashless dispersant a bit prematurely?
Thanks for suggestions!
Dan
Recommendations for switch from mineral oil to ashless dispersant
Moderators: sky's the limit, sepia, Sulako, lilfssister, North Shore, I WAS Birddog
Re: Recommendations for switch from mineral oil to ashless dispersant
If you have been running the engine hard as you should during break in I would assume its broken in but if you have been babying it i'd wait.
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arctic navigator
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Re: Recommendations for switch from mineral oil to ashless dispersant
You wont hurt anything to run the mineral oil until you get back from your trip.
Where people get into trouble is when they run an engine to 1200-1500 hours on mineral oil then switch. The additives in Ashless Dispersant cause carbon buildups in the engine to break loose plugging passages and oil filters, but at less than 100 hours there will be so little you wont cause any harm.
The first few flights are the most critical for break in. Everyone has an opinion as to how to do it successfully, but commonly you want to run the engine at MCP for the 25-50 hours. What level are you keeping the oil at and what is the capacity of your sump? Once the engine is broken in, if you have a 12qt sump I wouldn't add until your down to 9 or maybe even 8 then add a full quart at a time. Work your way down a little at a time and see where it stabilizes.
Have fun with your 10, it looks like a fun bird from the reading I've done.
Where people get into trouble is when they run an engine to 1200-1500 hours on mineral oil then switch. The additives in Ashless Dispersant cause carbon buildups in the engine to break loose plugging passages and oil filters, but at less than 100 hours there will be so little you wont cause any harm.
The first few flights are the most critical for break in. Everyone has an opinion as to how to do it successfully, but commonly you want to run the engine at MCP for the 25-50 hours. What level are you keeping the oil at and what is the capacity of your sump? Once the engine is broken in, if you have a 12qt sump I wouldn't add until your down to 9 or maybe even 8 then add a full quart at a time. Work your way down a little at a time and see where it stabilizes.
Have fun with your 10, it looks like a fun bird from the reading I've done.
Re: Recommendations for switch from mineral oil to ashless dispersant
Thanks for the responses!
I've been running the engine pretty hard for the past 35 hours - almost always at 75% power or better. I suspect it's broken in, but I never saw a sudden drop in CHTs or drop in oil consumption or any of the "standard" indicators. The oil consumption has been reasonable (at least, I think so), and though the CHTs are a bit higher than I'd like, it's just as likely I need to tweak my baffling as anything else. Lycoming did run the engine at the factory for something like 2 hours initially, and with my first couple flights, improving the baffling somewhat and initially having a fair bit of oil come out the breather tube before I started to sort out how much the engine wanted to keep in the sump made determination of break in with CHTs or oil consumption a bit fuzzy. I suspect most of the break-in happened before the 4-5 hour mark total time on the engine, where I was able to properly and consistently monitor things. I'm just wanting to make sure it's as broken in as it's going to get, since there's only the one chance to do it right.
The capacity of the sump is 12 quarts, but nobody I've heard of with the same engine (IO-540 D4A5) operates at even close to that. It seems like 8-9 is typical to avoid losing it through the breather tube. Mine seems to like it a bit lower, at around the 7.5-8 range, or relatively rapid oil consumption and a greasy belly indicate to me that it's just dumping the excess overboard. When it gets down to 7.5-8 or so, the belly stays cleaner and consumption goes down.
It's good to hear that going 10 hours over on the mineral oil shouldn't hurt anything - I'll change it out when I get back from my trip then.
I do have to say that the RV-10 is sure a fun and practical aircraft to fly. And it's nice to be past the initial 25 hour restricted period where I had to stay within 25 nm of home base - it doesn't take very long to bump into the walls..
Dan
I've been running the engine pretty hard for the past 35 hours - almost always at 75% power or better. I suspect it's broken in, but I never saw a sudden drop in CHTs or drop in oil consumption or any of the "standard" indicators. The oil consumption has been reasonable (at least, I think so), and though the CHTs are a bit higher than I'd like, it's just as likely I need to tweak my baffling as anything else. Lycoming did run the engine at the factory for something like 2 hours initially, and with my first couple flights, improving the baffling somewhat and initially having a fair bit of oil come out the breather tube before I started to sort out how much the engine wanted to keep in the sump made determination of break in with CHTs or oil consumption a bit fuzzy. I suspect most of the break-in happened before the 4-5 hour mark total time on the engine, where I was able to properly and consistently monitor things. I'm just wanting to make sure it's as broken in as it's going to get, since there's only the one chance to do it right.
The capacity of the sump is 12 quarts, but nobody I've heard of with the same engine (IO-540 D4A5) operates at even close to that. It seems like 8-9 is typical to avoid losing it through the breather tube. Mine seems to like it a bit lower, at around the 7.5-8 range, or relatively rapid oil consumption and a greasy belly indicate to me that it's just dumping the excess overboard. When it gets down to 7.5-8 or so, the belly stays cleaner and consumption goes down.
It's good to hear that going 10 hours over on the mineral oil shouldn't hurt anything - I'll change it out when I get back from my trip then.
I do have to say that the RV-10 is sure a fun and practical aircraft to fly. And it's nice to be past the initial 25 hour restricted period where I had to stay within 25 nm of home base - it doesn't take very long to bump into the walls..
Dan
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crazyaviator
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Re: Recommendations for switch from mineral oil to ashless dispersant
What are your cylinder compressions?
Re: Recommendations for switch from mineral oil to ashless dispersant
I haven't checked. Though good point - it probably wouldn't hurt to do so.
