Oil Analysis Question

[Matt M]

I just got my oil analysis results back from blackstone. Aluminum, Chromium, and iron all up significantly.  My aluminum, chromium, iron, and lead have been elevated since I started doing the analysis. I started at 84 hours since Lycoming factory overhaul, 168 hours on it now. I bought the aircraft after the engine was already broken in. Blackstone attributed the initial higher levels with cylinder break-in. They are recommending borescope and compression check. My compressions at annual in September were 77/78/78/77. Engine is running strong. I haven’t needed to add any oil since at all yet since I bought it. Thoughts?

Matt

[carusoam]

Matt,

I can’t tell…

Did you normalize the data to account for how many hours were on the oil itself…

If one oil change had 10 more hours than the previous oil change… you magically see 20% more metal concentrations for the same wear rate… if the one was at 50hrs, and the other was at 60hrs….

I only see one set of actual data…?

I don’t know what the second column really represents… the notes are missing/cut off…

The only real value to the oil analysis… is your engine being measured against itself, as uniformly as possible…

The numbers are so tiny… it is hard to get meaningful data when comparing it to other planes from other areas of the world during different seasons…

PP thoughts only, not a chemist… or metallurgist…

Best regards,

-a-

[hammdo]

Also, do you take a sample right away or do you let it drain about half out? That can also make a big difference. How does the filter look?

Lead can be high also if you run rich..

-Don

Edited April 23, 2022 by hammdo

[Matt M]

Here is the complete picture. The two samples to the right of the average column need to be swapped. I sent in two samples at once as and they swapped them. It should have been 4/27/20 and they thought it was 4/27/21.

 

Matt

[Matt M]

1 minute ago, hammdo said:

Also, do you take a sample right away or do you let it drain about half out? That can also make a big difference. How does the filter look?

Lead can be high also if you run rich..

-Don

I had my mechanic do this oil change. Not sure when he took the sample. He cut the filter and no metal.

[hammdo]

Borescope would be prudent...

-Don

[carusoam]

Engine Hours at Time of oil change?
 

84

104

139

168

Hours between oil changes…

1) 20

2) 35

3) 29

 

For more comparable numbers…

You may want to divide the measured ppm by the hours between oil changes…

This will ‘normalize’ the data… as concentrations always increase with the engine hours…

So take the hours out for comparison… 
 

Look closely at what the oil analysis company does for you… they might have another chart where they have normalized the data for better comparisons…

By the look of it…

the number of hours on each of the samples is greatly different… if Alexa did my math correctly…

without normalizing the data… it would be a big pain to have to change the oil at exactly at 35hours all of the time… 

Technically what we are usually looking for…are the big pieces that show up in the filter first… and wonder what kind of metal they are… it is kinda rare to have the oil analysis start showing interesting results prior to the parts showing up in the filter…

ppm is incredibly tiny numbers… in the real world of engine insides…

Some interesting numbers do occur around here… an air filter, not filtering the air… shows sand getting into the oil…  rubber intake seals that fall apart… show up as silicone in the oil….

So…. Don’t give up on the oil analysis…   but know how the tiny details make a difference to the numbers… including where and when you grab a sample… (pointed out above)

Best regards,

-a-

[A64Pilot]

Every engine will be different, that’s why oil analysis is really only valid when you have several succeeding analysis to compare the new one against, your not looking at numbers, your looking for large sudden changes. Some engines run high numbers and are perfectly good engines and later in life the numbers may or may not drop, conversely some engines run low numbers and may or may not increase later in life, but both engines upon tear down are perfectly fine.

In my opinion there is way too much concern about oil analysis, in almost 20 years of maintaining a fleet of aircraft in the Army, I never removed a component based on oil analysis, we removed many components but it was always other warning signs that caused us to, usually visible metal flakes in the oil “glitter”

To settle your concerns give Lycomings help desk a call, contrary to beliefs on the internet they know quite a bit about the engines they manufacture. Listen to what they have to say, it’s a free call and you will talk to a knowledgeable person not someone at a call center with the same manual you have.

Having said that a borescope is inexpensive and non-invasive and isn’t a bad idea, it’s possible that your rings didn’t seat well, if your sitting for several minutes at high idle warming up the engine, stop, pre heat if needed but don’t sit warming it up, and go out at less than 5,000 ft altitude if possible and run the snot out of it for a few hours, at takeoff power, run it rich and of course watch cyl head temps.

A can of Marvel Mystery oil in the oil wouldn’t hurt either, it’s not approved, but I’ve seen it help more than once if the cylinders are glazed.

Glazed is a thin layer of varnish from fuel and or oil cooked onto the cylinder, only cause of glazing I’ve seen comes from people thinking they are doing the right thing and warming up the engine until oil temp begins to move on the gauge, but as there is very little cooling, the cylinders can overheat even though cyl head temp isn’t high

Edited April 23, 2022 by A64Pilot

[Matt M]

20 minutes ago, A64Pilot said:

Every engine will be different, that’s why oil analysis is really only valid when you have several succeeding analysis to compare the new one against, your not looking at numbers, your looking for large sudden changes. Some engines run high numbers and are perfectly good engines and later in life the numbers may or may not drop, conversely some engines run low numbers and may or may not increase later in life, but both engines upon tear down are perfectly fine.

In my opinion there is way too much concern about oil analysis, in almost 20 years of maintaining a fleet of aircraft in the Army, I never removed a component based on oil analysis, we removed many components but it was always other warning signs that caused us to, usually visible metal flakes in the oil “glitter”

To settle your concerns give Lycomings help desk a call, contrary to beliefs on the internet they know quite a bit about the engines they manufacture. Listen to what they have to say, it’s a free call and you will talk to a knowledgeable person not someone at a call center with the same manual you have.

Having said that a borescope is inexpensive and non-invasive and isn’t a bad idea, it’s possible that your rings didn’t seat well, if your sitting for several minutes at high idle warming up the engine, stop, pre heat if needed but don’t sit warming it up, and go out at less than 5,000 ft altitude if possible and run the snot out of it for a few hours, at takeoff power, run it rich and of course watch cyl head temps.

A can of Marvel Mystery oil in the oil wouldn’t hurt either, it’s not approved, but I’ve seen it help more than once if the cylinders are glazed.

Glazed is a thin layer of varnish from fuel and or oil cooked onto the cylinder, only cause of glazing I’ve seen comes from people thinking they are doing the right thing and warming up the engine until oil temp begins to move on the gauge, but as there is very little cooling, the cylinders can overheat even though cyl head temp isn’t high

My first step is to send in another sample. I got about 14 hours on the oil since the last sample.  I talked to my mechanic this morning who thinks he may have screwed up obtaining the sample. He is second guessing himself. I echo Lycoming support. A few weeks ago I attended a seminar at Sun ‘n Fun given by Lycoming field tech support. It was a very informative session. 

[Fly Boomer]

oil chg dt      tot hrs      hrs since last
12/07/2019     84
04/27/2020    104           20
01/26/2021    139           35
03/22/2022    168           29

Intervals are close enough for direct comparison.  Al, Cr, Fe, and Pb all took a significant jump.

Might be time to let Lycoming factory know that something appears to be amiss, and see what they recommend.

EDIT:  When I read further down, I see that Anthony @carusoam and @A64Pilot already made these observations.