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-   -   Oil Changes (https://vansairforce.net/community/showthread.php?t=103832)

RickWoodall 09-02-2013 04:15 PM

thoughts
 
I am not sure what the advantage is of changing oil and filter at 25 hours if the plane flies a lot? Hangar queen yes...but if you fly...lots, 25 hours is nothing..I can knock that off in a week of fun.
Its not about the money, but I just dont see the benefit. Is it real, or just something that oil and filter firms promote to burn up product? From an engine point of view...25 hours is absolultely nothing...its a few days of running at 4-6 hours of flying. I stick closer to 40-50 hours and through the heavy flying times.....keep doing it but wonder if its really necessary. The filter and oils are supposed to be so good, 25 hours isnt even a fair break in period is it? From a car, or tractor, or boat etc engine....25 hours is crazy short. Yes i know lead...but if plugs arent fouled....and all is good and its a low time engine....what benefit is there or how do you measure that that is worth the trouble and cost? I am not one to just do things cause someone said to...what is the reason. Does the oil break down in 25 hours...does the filter really get filled up in 25 hours. Cut one open and show me a diff between 25 and 50. Is it measurable?

Just asking...will keep buying oil and filters, no issue but not sure its money well spent.

GhostRider32 09-02-2013 04:22 PM

A sample sent to blackstone-labs.com can give you a detailed analysis of your oil and tell you what % of your oil life is used as well as any metals in the oil. Then you can have a scientific idea of how often you want to change your oil.

RV-4 09-02-2013 05:59 PM

Oil Change Interval
 
The two links provided by Gil # 12, are really useful I would say...

I would assume that Lycoming know a thing or two about their engines..
-----------------------------------------
The Lycoming service bulletin also has a 4 month oil change requirement if you don't reach the 50 hrs.

http://www.lycoming.com/Portals/0/te...Inspection.pdf

Also recommended by Mike Busch -

http://blog.savvymx.com/2010/03/changing-oil.html
------------------------------------------------------------------
I will go with the 25 hrs inspection for the next two or three o?l changes since the engine has just been top overhaul) and monitor the o?l quality and take it from there.

The main reason behind keeping the filter is not cost ( very minimal in the operation of an A/C ) but more to avoid as much as possible the potential mess when removing it...

I will make myself a special tray to pick up as much of the o?l as possible..

Thanks again, I appreciate the info.

Bruno

luddite42 09-02-2013 06:33 PM

If you have inverted oil (slobber pot), 25 hrs is typical, since most of the crankcase puke gets returned to the sump. Even with a filter, oil is pretty dirty after 25 hrs.

LifeofReiley 09-02-2013 06:46 PM

Quote:

Originally Posted by Mel (Post 803645)
Obviously I have a different take on oil/filter changes then many here, but I will never change oil and run it through a dirty filter.
I will always change the filter any time I change the oil.

+1 with Mel... :)

Don't put the TP back on the roll either.

dealfair 09-02-2013 07:15 PM

Quote:

Originally Posted by John RV8 (Post 803663)
I'm with Mel on this one. I would never change the oil without changing the filter.

Not aircraft engines but as another data point I know most long haul diesel trucks change their filter between oil changes....

Ditto me too! :)

RV8RIVETER 09-03-2013 08:51 AM

Sounds like a good experiment
 
Lycoming also says, do not run LOP..... Not saying the 25/50 is not correct, but I would bet it is based on oils and fuels of the 1930s. The 3k car oil change has proven be no longer valid.

I read an experiment years ago by an engineer who owned a SHO Taurus and was testing different synthetic oils for lifetime. IIRC, he sampled every thousand miles and sent to lab. Mobile 1 and Amsoil were good for over 10k miles. Another interesting tidbit was that the highest metal (wear) in the samples was the first one after an oil change.

One would think that variables such as; how often flown, what is the average oil temp, type fuel, type oil, would be the big ones. Could be a good experiment to send samples every 10 hours to see how oil chemistry changes.

I don't fly regular enough right now, but for those that do, it also might make a good article. hint hint ;)

zilik 09-03-2013 09:10 AM

Quote:

Originally Posted by Mel (Post 803645)
Obviously I have a different take on oil/filter changes then many here, but I will never change oil and run it through a dirty filter.
I will always change the filter any time I change the oil.


I'm with Mel on this one. At first I was in the 25/50 camp changing the filter every other oil change. Then I thought about my cars and I have never changed the oil without changing the filter so why would I skimp on the expensive engine in the plane.

So I shoot for 25 hour interval and don't sweat it if I hit 30. Oil and filter at each change.

While I could go 50 my oil usage goes up as the oil gets older. I dump 8 quarts in when I change and the first goes away in about 13 hours. The second quart is gone at hour 25 and I know its time to change without looking at the logbook.

Works for me.

SHIPCHIEF 09-03-2013 05:03 PM

I'm generally in the 25/50 camp, having planes both with filters and without.
But if you burn a lot of Mogas, you could probably go longer. Without TEL to strip the tin off your pistons etc, Mogas will damage the oil more slowly. Still, I follow the 25/50 guide, and change early if it's close at the condition inspection or I have a trip planned that will take more time than the remaining hours on the oil.
I would like to add a comment about sludge build up. These Lycoming engines have a flat bottom sump. When we take off the sump (2 engines, so I'm not a big expert) there is a fair accululation of carbon sediment in the bottom. One engine was opened to install an inverted oil system. The sediment would need to be cleaned out in this case, because inverted flight was intended. But it would be a good idea to remove and clean the sump at some interval, maybe mid-time?

GLPalinkas 09-03-2013 06:34 PM

Quote:

Originally Posted by zilik (Post 803929)

While I could go 50 my oil usage goes up as the oil gets older. I dump 8 quarts in when I change and the first goes away in about 13 hours. The second quart is gone at hour 25 and I know its time to change without looking at the logbook.

Works for me.

Gary, you have a ton of experience and have been flying your plane a long time but could it be that you are losing oil to blow out? I know on my Lyc O-360 if I put more than 6 qts in it I lose it thru the case breather tube. My stock Van's breather tube, by the way, needed to be rotated so that it exits higher than the case which also stopped a lot of oil loss. When I first started putting 8 qts in my engine it would drop in 15hrs to 6 qts level and then it would not use/lose any oil after that. Just a thought.


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