How to Inspect an Aircraft Oil Filter the Right Way

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Why Oil Analysis Alone Won't Save Your Engine

Oil analysis is an indicator, not a verdict on airworthiness. John and Jeff break down why the report is just one tool, and what you have to do alongside it to actually know what's happening inside your engine.

More owners and pilots are leaning on oil analysis like it's the final word on engine health. It isn't. Both Lycoming and Continental tell you to inspect the oil filter — cut it open, flush the media, run a magnet through it, and look at what your engine is actually shedding. John and Jeff walk through the full routine: how to take an oil sample correctly (always midstream, never the first or last of the drain), why letting the drained oil settle in a clean five-gallon bucket and filtering the last bit through a coffee filter tells you what's really sitting in the sump, and why pictures of every filter and screen inspection beat trying to remember what last quarter looked like. They cover the difference between ferrous and non-ferrous debris, why a high iron reading after a winter of sitting often just means corroded cylinder walls getting scraped clean, and the Lycoming brass bushing AD covering engines built between 2009 and 2015. They also get into the part most owners skip entirely — the finger screen — and why it catches the big chunks an oil filter never will. If your filter has a bypass valve and you're making metal between long oil changes, that material can route straight to your bearings without you knowing the bypass ever opened.

In this episode, we cover:
- Why oil analysis is an indicator, not an airworthiness determination
- How to take an oil sample correctly — midstream of the drain, every time
- Cutting open the oil filter, flushing the media, and running a magnet through the debris
- Letting drained oil settle and filtering the last 5% through a coffee filter to see what's really in the sump
- Why you need to photograph every filter and oil inspection, not rely on memory
- Telling ferrous from non-ferrous debris and what each suggests
- Why finger screens catch failures the oil filter will miss
- The Lycoming brass bushing AD on engines built 2009–2015 and why you watch the oil for brass
- How shorter oil change intervals reduce the risk of the filter bypass dumping debris into your bearings

For piston aircraft owners who want to catch problems early instead of being surprised by them — this is how you actually read what your engine is telling you.

TIMECODES
00:00 The oil sampling mistake that wrecks your data
00:38 Why oil analysis is an indicator, not airworthiness
01:35 How to inspect your oil filter the right way
02:28 Reading what's left in your drained oil
03:20 When elevated readings don't mean engine trouble
04:07 The catastrophic failure oil analysis missed
05:17 Taking samples midstream and staying consistent
05:55 High iron after winter — what it usually means
06:48 What chrome, nickel, aluminum, and molybdenum tell you
07:39 Lycoming and Continental limits on filter debris
08:12 Saving filter elements in baggies for comparison
08:51 Why finger screens still matter and why mechanics skip them
09:39 Filter, screen, or both — what to inspect and why
10:31 The Lycoming brass bushing AD (2009–2015 engines)
11:14 What the finger screen catches that the filter won't
11:37 Why the filter bypass valve is the hidden risk

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