We often speak of oil analysis and as much as I believe in it, I don't know much about how the lab works. I found this link from another website, but it appears that the technology is relevant to aircraft as well.

https://bobistheoilguy.com/


JB

Cool article. The main thing I don't understand is how it only costs $28...

I'm so torn on oil analysis. I have a couple customers that have had can oil samples on heavy equipment and have engines blow up. My dad is currently in the process of having his Cat engine in his peterbilt rebuilt, and it has ony ever returned can oil analysis tests. For me to send hem out for my plane costs about $150 up here in Canada, so I have a hard time with it, so do my customers that have been burned by it in heavy iron. Has anyone on here positively benefitted from it?

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Mike Busch of Savvy Aviation recommends foregoing oil analysis. Reading on beechtalk, it seems to be very very few that have found things in oil analysis that could be resolved early. One person recounted that they got something that they were told was bottom end from analysis and torn engine down to find out it was in the top end. Another said about every fourth analysis was bad, but the other three said the motor was in great shape. YMMV...

My opinion: they're a diagnostic tool that is best used along with other diagnostic tools. If you have an engine running smoothly with no problems, I wouldn't act on a negative oil analysis. But if you've got a suspected issue supported with other diagnostic tools, then I'd take a negative oil analysis seriously and use my best guess from all the data present to make a repair plan.

The DoD sends oil samples for testing on all it's equipment.

Air Force Technical Order (T.O.) 33-1-37 is the bible for oil analysis. You can Google "joint oil analysis program" and it'll pull up links to
access the different volumes in .pdf format. Volume I provides a good overview of oil sampling.

The key ingredient in oil analysis is trend analysis; i.e., if you don't religiously/regularly submit oil samples at regular oil change intervals to establish "wear" patterns for your engine then IMHO oil analysis is much less useful. It's much more useful as a diagnostic tool when used as a regularly scheduled preventive maintenance function than as a random troubleshooting tool.

CamTom12 wrote:My opinion: they're a diagnostic tool that is best used along with other diagnostic tools. If you have an engine running smoothly with no problems, I wouldn't act on a negative oil analysis. But if you've got a suspected issue supported with other diagnostic tools, then I'd take a negative oil analysis seriously and use my best guess from all the data present to make a repair plan.

The DoD sends oil samples for testing on all it's equipment.

I agree that it's a trend monitoring tool. But I've seen more guys have clean oil samples every time and then have their engine blow up or need rebuild. But maybe that's just the dealers saying they are can to avoid warranty work...

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Maybe a 3rd party analysis company should get involved! Haha

Maybe Cam! It would be fun to send the same samples to another company and see what they say. If we still had them I would.

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I've followed bobistheoilguy for years after my last aircraft engine cam job. The advice for trend analysis is good, and actually few that post there ever have something blow up on them unexpectedly. Mostly it's populated by well meaning folks obsessed with oil and lubricants.

I had two premature O-320 Lycoming engine overhauls due to cam wear, lifter spalling, and piston scoring . None were caught by oil analysis done prior to the teardown. No long term trend analysis was available so no fault of the analyzers (Blackstone).

What was available was the onset of visual metal in the drain oil but nothing in the oil screen. No oil filters were installed. The oil looked like someone had dumped in some silver fabric dope...not much but enough reflective sheen to be seen in bright light or by a flashlight beam shone in the drain bucket. The oil screen did eventually catch the chunks but by then it was over.

Some of the metallic sheen was aluminum that a magnet wouldn't attract, but the rest was metallic from the cams and lifters. Having a magnet somewhere in the oil system would go a long ways towards visibly monitoring wear metals.

Gary

To Gary's last bit there, I recently discovered that Tempest filters have a "donut" magnet inside of them. I just ordered a couple for my next oil changes. Previously (and currently on the fresh oil change) I have been running Champions.

The filter magnet is a good start. There are commercial external wrap-around magnets for oil filters as well. But still it takes cutting and evaluating the filter's contents...maybe even saving the remnants but that may a bit anal.

For engines not needing a quick drain there are replacement drain plug magnets. For example: http://www.drainplugmagnets.com/magneti ... gshome.php

One of my inventions that never saw light was a hollow slip-on magnet for the oil dipstick. Fasten it with high temperature epoxy or whatever so it sees oil. Easy to read.

At least have a look at your drain oil for any visible suspended metal or do long term oil analyses. The problem with oil analysis is if they see an excessive trend they will tell you to monitor and resubmit samples periodically. By then it may be too late and a cylinder pull is indicated.

Gary

[quoteAt least have a look at your drain oil for any visible suspended metal or do long term oil analyses. The problem with oil analysis is if they see an excessive trend they will tell you to monitor and resubmit samples periodically. By then it may be too late and a cylinder pull is indicated][/quote]

- That illustrates my point; oil analysis is meant to be a preventive maintenance tool, not a troubleshooting tool. In order for oil sampling to be effective samples need to be submitted at every oil change. The whole point of oil sampling is to predict failures as opposed to identifying existing ones. If you're thinking about burning a sample when a problem has already occurred then I agree with saving some cash and just opening the filter (which really ought to be done on every oil change anyway), pulling jugs, and inspecting the crankcase.

I've been doing oil analysis on the engine in my 180 hp C170B for a totally different reason. I bought it at 1850 SMOH and should have it for sale when my C180 project is finished at right around TBO. An analysis report with no abnormalities showing will help a potential buyer to have a "warm fussy" feeling about a high time engine and make selling easier. The purpose of trend monitoring, which is what oil analysis is part of, is to prevent catastrophic failure by telling you that something is going wrong so that the engine can be removed from service. This protects the safety of pilots, passengers and airplanes. Similar results are accomplished by checking for metal in the oil screen or filter. It will not save the engine but probably will reduce the cost of overhaual by preventing damage to expensive parts by metal carried throughout the engine by the oil. A perfect example would be results showing copper, which could possibly be from the copper plating on the main and rod bearing shells between the steel shell and the bearing material. It would be prudent to do further investigating of the source and if verified
remove the engine from service for repair or overhaul before nonrepairable damage to the crankshaft developed.

Tim

Here's an observation from Blackstone Labs regarding brands of aircraft oil:

http://www.blackstone-labs.com/about-aircraft-oils.php

Essentially the same performance using their criteria.

In addition to wear metals over time and basic oil contents like anti-wear or dispersant additives, insolubles is a critical test. It can infer blow-by past pistons and exhaust valve guides as the engine wears. Rings and valves can stick due to the buildup of combustion deposits. Oil filters can capture the carbon chunks and should be examined at changeout:

http://www.blackstone-labs.com/what-are-insolubles.php

Gary

Used to just cut open filters and roll them out on cardboard, let oil seep away then light spray of eather (Diesel quick start) Magnifying glass observation and small magnet.
Would not run an engine without a filter anymore.
Did early on with old 65-90 hp engines. But was young and stupid
and just followed the older crowd.

Chirs C

The mechanic I use doesn't think much about oil analysis. He has seen engines fail despite a good oil analysis. He much prefers to tear

apart the oil filter and inspect it visually and with a magnet.

ShadowAviator wrote:The mechanic I use doesn't think much about oil analysis. He has seen engines fail despite a good oil analysis. He much prefers to tear

apart the oil filter and inspect it visually and with a magnet.

The two don't have to be (and shouldn't be) mutually exclusive.

CamTom12 wrote:

ShadowAviator wrote:The mechanic I use doesn't think much about oil analysis. He has seen engines fail despite a good oil analysis. He much prefers to tear

apart the oil filter and inspect it visually and with a magnet.

The two don't have to be (and shouldn't be) mutually exclusive.

I agree. Nothing wrong with more info.

A good way to look at it is that a good analysis doesn't necessarily mean your okay, BUT a bad analysis definitely means there is an issue.