Any A&Ps out there question oil change

newmei

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Hello, just did a oil change on my 0-300A on my C-172A, found a little carbon (non-metalic) and tiny tiny bit of ferrous metal that was stuck in a section of the screen. The metal was only about 1/4 to 1/2 the size of a erasor in a pencil and was ground up finely-to coarse. Is this anything to worry about??? I don't think so from my expierence. It appeared that maybe the screen was'nt cleaned well and it kinda clung to that area of the screen....

Thanks
 

mnboyev

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I dont want to lead you the wrong way.. but I would say that is normal for that engine. I had a 61 172 with an O-300D. That sounds about right. A little carbon or gook in the screen every 20 hrs was normal. However, I would get a bit worried if every change I found pencil eraser size metal chuncks !!! Send out an oil sample to one of those many testing firms.. They'll tell you whats going on... How much time on the old girl.... I worried more about the cylinders and valves on my 'fast back' hawk.

AP first... Pilot second.. EVV
 

dogg

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It is not so much what you found this time as the trend. What did it look like 100 hours ago what will it look like 100 hours from now etc.... spectranalysis which is I believe what the oil sampling is called will tell you what types of metal are found in your oil sample and then from there a call to Continental to ask them where those types of metal are found will tell you what might be going on. Again it is more a trend and not so much what each sample shows that you are looking for. Not to say that large chunks of metal are not a concern whenever and where ever you find them. What you have described sounds normal to me. Some other things that can change a reading are cold starts or running very rich
 

avbug

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Newmei,

From a mechanic's perspective, it's impossible to tell you about what you found without seeing it. However, generally speaking, the only thing your oil screen will actually screen out is anything big enough to have a part number. Smaller than that, and it bypasses the oil screen anyway (figuratively speaking).

You can do yourself (and your engine) a favor by purchasing and maintaining an STC'd full-flow spin-on filter adaptor.

The type of metal you found is important. The first thing you want to determine when investigating metal chips or particles is weather or not the material is ferrous. Use a magnet. If it sticks, it's ferrous. This gives you a start in determining what you have. From there, it becomes a process of elimination. In your case, you've determined it's ferrous; now you need to determine what it is.

It's important to remember that you've located one piece. There are almost certainly more pieces. I would run your oil through a screen when it's drained, to see what else comes out. It may or may not have all made it to your oil screen on the engine. Use a piece of household screen to sift the oil for other bits of debris as it drains into a bucket. This generally works best if the screen s in a funnel, or similiar device. You can put it in a cut open oil can, and run it through that, barring anything else.

Where there is one piece, you often will find more. The question arises what will happen if these parts go through the oil pump gearing, or arrive at a bearing journal...or get stuck in an oil galley. Nothing good can come of it. It sounds as though you may have part of a gear tooth there.

Change your oil every 50 hours or three months, whichever comes first. If you don't fly a minute in three months, change the oil anyway. I prefer 25 hour oil changes in airplanes.

Start on a regular oil analysis program. Take a sample every oil change, and submit it. Keep a compilation of the reports. A single report won't necessarily tell you anything about the engine, but a trend and a baseline will. Get to know what the engine is producing, and check for changes. This is one of the single most valueable things you can do for that engine as an owner, after regularly changing the oil, and operating the engine responsibly.

As for carbon, you'll see a change in carbon in the filter if you've changed types or grades of oil, or have switched from mineral to multigrade, etc. If you're going from straightweight to multigrade, be prepared to begin seeing more deposits.

Change your oil often, and ALWAYS take samples for submission. Good luck!!
 

newmei

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Thanks for all the advice guys...

Keeping in mind that this aircraft has flown more in the past four months than it has in the past four years also is something to point out. That would probably account for some of the carbon would be my guess. For now we'll just keep a eye on the screen and possibly do the oil analysis.
 

newmei

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Also the ferrous metal pieces were in pieces the size of glitter, BUT clumped (like the screen was'nt cleaned well) to area of 1/4 a pencil erasor. (rather the erasor on a pencil) On our last airplane we did oil and filter changes at 25 with pretty good results. If I do my car at short 3000 miles intervals you better bet I'm going to do a change of oil on a engine that costs 11,000 plus at short intervals too.


I have actually a unrelated question but pertinent out of curiousity. What effect does a 35 year old engine with the same time of a 2 year old engine have to do with reliablity and safety. I hear various opinons on this, with some common concerns about corrosion for inactivity (such as the cam and the cylinder barrels, etc)

Thanks
 
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