Oil Analysis

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ahramin
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Oil Analysis

#1 Post by ahramin » Wed Aug 16, 2017 11:53 am

Trying to figure out what to do with my oil analysis data from the lab. I figure Shell would be a good place to start so I drill down on their website and find the following for aviation questions:

http://www.shell.com/business-customers ... ation.html

Am I the only one that sees a totally broken page? Links don't link, text missing.
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robertw
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Re: Oil Analysis

#2 Post by robertw » Wed Aug 16, 2017 12:20 pm

Every engine is different and will show differing metal contents in the oil. What's in the oil will vary based on a number of factors like storage / operating conditions, usage, proper warm up / cool down procedures, type of oil, condition of oil and on and on... Looking at 1 lab test really isn't too helpful. Oil analysis is best viewed to determine trends, so it's best to look at the history of lab results for your engine together. If you see the Cr, Fe, or Al levels creeping up at every test, your engine is getting tired and may need repair.

You might want to give a shop that O/H's your engine type a call to see if they can give you an idea as to what's normal, but like I said, normal varies from engine to engine and really, you have to establish "normal" for your own engine.
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helicopterray
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Re: Oil Analysis

#3 Post by helicopterray » Wed Aug 16, 2017 12:39 pm

We've been using these guys:

http://www.spectro-oil.com/

As mentioned, oil samples are used for trend analysis. Compare each sample with the previous one to see an abnormal spike in any of the metallic particles to see what's breaking down.
You can order a pre-paid kit. Fill out the info for the engine or component, they send you the results.

http://www.spectro-oil.com/Analysis-kits-aviation.html
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cgzro
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Re: Oil Analysis

#4 Post by cgzro » Thu Aug 17, 2017 5:15 am

I gave up on oil analysis after my first overhaul. I was getting higher Fe in the analysis but my mechanic said we'd keep an eye on things. Then it started making physical indications of problems, more blow by, fouling etc. and then finally flakes in the oil filter.
The second overhaul was due to cracks in the case which would not have shown up in the oil analysis.

So at least in my case, for the two overhauls I've had, the oil analysis was unnecessary and frankly just increased my stress level unnecessarily. The engine gave plenty of other warnings.

Perhaps with other failure modes its more helpful, I don't know, perhaps bronze bushing material tells you of impending crank bushing or con rod bushing failures but very high oil temperatures and lowered pressure are also good indicators of bushing problems.

Anyway currently I'm not doing them.
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Broken Slinky
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Re: Oil Analysis

#5 Post by Broken Slinky » Thu Aug 17, 2017 6:06 am

Wear Check is another company that does oil analysis. https://wearcheck.ca/

I'm with helicopterray. It's more about the trends than anything. Mine for example shows slightly abnormal nickel levels which is indicative of valve wear. It is a trend I have been following for 3 years now. Talking with other identical engine owners, they're seeing similar numbers and getting TBO and higher without issues. Cutting open the filters is just as important. It gives you a trend as well.
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Re: Oil Analysis

#6 Post by cgzro » Thu Aug 17, 2017 6:28 am

Cutting open the filters is [b]more[/b] important than oil analysis IMHO. I.e. you can see the actual pieces and their sizes. Note that you can have largish amounts of metal in the screens and filters and still not see horribly high amounts in the oil analysis. I noticed this when my cam was going. I got a years worth of high Fe readings way before, then it dropped back to normal, right about the time I started to get slivers of Fe in the screen. So for cam problems anyway I felt that the oil analysis was a waste of time but the screen was essential.

Actually every time I do an oil change I drain my oil into a funnel with a fine metal screen to see what came out, and of course I check the oil screen upper and lower.
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ahramin
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Re: Oil Analysis

#7 Post by ahramin » Thu Aug 17, 2017 9:11 am

Speaking of screens, I always check my screen in the sump during the oil change but just found out about the upper "pressure" screen. Is is possible that the upper screen is still installed even though the engine has a spin on oil filter? If so then is it possible to inspect this screen when changing the filter? Engine is O-320-E2D.
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Re: Oil Analysis

#8 Post by cgzro » Thu Aug 17, 2017 1:46 pm

Can't speak to the O-320 but the IO-360 upper screen housing is removed and replaced with a spin on filter fitting so the two cannot co-exist on the IO-360 accessory case.

IMHO you should always be cutting open the oil filter after oil changes and also draining the oil through a screen not just directly into a bucket. Oil analysis is not a substitute for checking the filters because you won't necessarily see increased metal in the oil analysis when a chunk breaks free and gets stuck in the filter!
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JasonE
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Re: Oil Analysis

#9 Post by JasonE » Fri Aug 18, 2017 5:45 pm

O-320 is the same. Upper screen gets removed for filter housing.
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ahramin
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Re: Oil Analysis

#10 Post by ahramin » Tue Nov 07, 2017 3:05 pm

So I have the choice of the following analyses:
Recirculating Lubrication Systems Package – ICP Metal Scan, Viscosities at 40⁰C and 100⁰C, Visual Inspection, Oxidation/Nitration/Sulfation (Infrared Scan), Moisture by Karl Fischer (If Crackle Test for Water is Positive), Total Acid Number, ISO Particle Count
$39.00/sample
Complete Analysis Package - ICP Metal Scan, Viscosities at 40C and 100C, Visual Inspection, Oxidation/Nitration/Sulfation/Soot (Full Infrared Scan), Crackle
Test for Water, Fuel % by Gas Chromatography (If Fuel Dilution is Suspected), TBN and TAN, Iso Particle Count or Patch Test
$56.00/sample
Basic Wear Package - ICP Metal Scan, Viscosities at 40C and 100C, Visual Inspection, Oxidation/Nitration/Sulfation/Soot (Full Infrared Scan), Crackle Test for Water, Fuel % by Gas Chromatography (If Fuel Dilution is Suspected)
$25.00/sample
On general principle I was going to ignore the complete analysis package which leaves me with the choice of spending an extra $14 on Total Acid Number and ISO Particle Count. No idea what the ISO Particle Count is unless it's something about not freaking out the border gaurds with nuclear bomb detectors when I'm clearing customs. I like the idea of getting a reading on the acid number as the plane is parked outside and I only do an oil change every 4 months. Does anyone else doing oil analysis do an acid test? Ever seen worrying numbers? I'm considering doing the acid test for the first 3 samples and if everything looks good dropping it in the future.

Wow. I really hate the quotes on this new forum format.
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Re: Oil Analysis

#11 Post by robertw » Wed Nov 08, 2017 3:05 pm

The only thing I've ever looked at on recip engine oil analysis is what metal is in the oil and then look for trends on the content of those metals. Chrome, ferrous metals, aluminum, magnesium, brass etc...

All that other stuff seems like marketing propaganda to me. ISO Particle Count? Crackle test for water? Gas Chromatography? I have never even thought about those things when trending GA recip engines.
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