by Jgibson » Thu Nov 03, 2022 3:28 pm
That's because the screen has a micron rating of 50+ whereas a good paper filter has a 25 micron or better rating.
But even when a screen catches debris, you have to examine it with a 10x magnifier and magnet to actually see what that debris consists of.
The 'failures' you see aren't the problem because whether you see them or not, the damage is already beginning and nothing you do can reverse that. Whether it's a filter or oil analysis, both are simply giving you a heads up to damage that's already beginning. The analysis gives better insight into WHAT the wear material is so you can make a better informed decision on exactly WHAT is wearing out.
I've always used the 25 hour oil and filter or oil and screen schedules but a paper filter will indicate 'issues' much sooner than a screen. Eventually that screen will show metal, but either way you're not going to reverse what is going on. Either will catch the odd debris such as silicone (an absolute no no on these engines) or pieces of paper towels, etc.
Screens do the job but just not as efficiently as a modern 'quality' paper filter. And if you got another 1600 hours out of an already 2200 hour cam on an 0-200, than you are extremely fortunate but that's certainly not the normal case. I've owned many of the small Continentals and have rebuilt and serviced hundreds. The cases wear (as there are no cam bearings) and eventually the cam moves around enough to start wearing itself and the lifters.
Small bits of carbon are exactly what you should see in either a filter or screen. Occasionally you'll get a small fleck of aluminum from a piece of case flashing but it's nothing serious. Steel is either cam, crank, gears, oil pump gears. Bronze is bushing material from rods, rockers, main bearings.
Joe