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Guys,
After owning various acft for the past 27 years and always "hiring a guy"
to fix them as I am all thumbs, I have met a lot of good (and some not so good)
mechanics. Paul Brevard, owner/operator of Spruce Creek Air Service, is
one of the most knowledgeable guys I have met when it comes to acft
engines. He was the editor of "Light Plane Maintenance" for many years and
worked at a well respected engine overhaul shop before that rebuilding thousands
of engines. I have very high regard for his opinions and comments.
I asked him to comment on the oil filter versus screen issue. His
comments are below.
Glen Davis CFII
Grumman Tiger N70GD
1946 Ercoupe N3103H
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_________(*)_________
o o o
Grumman Tiger N70GD
1946 Ercoupe N3103H
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_________(*)_________
o o o
Paul's comments:
1. Changing your oil every 25 hours will do more to reduce normal wear
patterns than anything else. No amount of filtration, additive package, or
operational consideration can do as much.
2. Normal wear elements are not detrimental to engine health.
3. Abnormal wear elements (cam spalling, bearings distress, etc) will
generate contaminants that can cause operational issues for any
engine-filter or no filter.
4. Filters and screens will catch some of the debris (normal and abnormal),
but none will catch all. You cannot filter all contaminants and still
provide adequate flow.
5. Modern oils contain additive packages that perform better than the
engines in which they are used. The very best synthetic or semi-synthetic
oil will not generate an advantage over a moderately-priced oil when the oil
is changed every 25 hours or less.
6. Sulphur compounds are a by-product of combustion. When in the presence of
water, these compounds form a derivative of sulphuric acid. These compounds
attack nitrided parts. These compounds can only be removed by draining the
oil. No amount of filtration will eliminate these acids.
7. Engines with excessive oil consumption will generate more of these acids
than desirable.
8. The greater the filtration (as related to media density and micron
elimination), the greater the amount of time the filter is in by-pass
(start-up, warm-up, etc).
9. Measured in microns, a filter is about 10% more efficient than the
standard screen.
10. And finally, oil filtration is a compromise.
CHANGE YOUR OIL EVERY 25 HOURS! MORE OFTEN IF YOUR ENGINE IS CONSUMING MORE
THAN 1 QT EVERY 4 HOURS!
patterns than anything else. No amount of filtration, additive package, or
operational consideration can do as much.
2. Normal wear elements are not detrimental to engine health.
3. Abnormal wear elements (cam spalling, bearings distress, etc) will
generate contaminants that can cause operational issues for any
engine-filter or no filter.
4. Filters and screens will catch some of the debris (normal and abnormal),
but none will catch all. You cannot filter all contaminants and still
provide adequate flow.
5. Modern oils contain additive packages that perform better than the
engines in which they are used. The very best synthetic or semi-synthetic
oil will not generate an advantage over a moderately-priced oil when the oil
is changed every 25 hours or less.
6. Sulphur compounds are a by-product of combustion. When in the presence of
water, these compounds form a derivative of sulphuric acid. These compounds
attack nitrided parts. These compounds can only be removed by draining the
oil. No amount of filtration will eliminate these acids.
7. Engines with excessive oil consumption will generate more of these acids
than desirable.
8. The greater the filtration (as related to media density and micron
elimination), the greater the amount of time the filter is in by-pass
(start-up, warm-up, etc).
9. Measured in microns, a filter is about 10% more efficient than the
standard screen.
10. And finally, oil filtration is a compromise.
CHANGE YOUR OIL EVERY 25 HOURS! MORE OFTEN IF YOUR ENGINE IS CONSUMING MORE
THAN 1 QT EVERY 4 HOURS!
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