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Reprinted from the November '92 issue of _european car_ magazine
and is a "side bar" to "Project 924", a well worn 924 that they
Fram oil filters
For the last several years, we have recommended Fram Wear Guard oil
filters because of the protection they afford automobile engines. Now,
Fram has come out with an improved oil filter, which goes by the name
Fram filters have always had good single-pass efficiency ratings.
The higher the single-pass efficiency, the more particle will be removed
from the oil each time the oil passes through the filter. Screen type
surface filters have poor single-pass efficiency, while depth filters
(such as "toilet ((no, not toyota, ed.)) paper" filters) generally have
high singel-pass efficiency. During Fram's on-going testing program, they
determined that single-pass efficiency is one of the best ways of
determining filter effectivness. Thus, the goal was to better their already
good single-pass efficiency.
The trade-off is that as single-pass efficiency rises, restriction often
rises, too. Thus, a screen-type filter (when clean) offers little restriction,
while a "toilet paper" filter is very restrictive.
To increase single-pass efficiency while controlling restrictiveness,
Fram switched from their highly evolved resin-coated cellulose fiber
element to a hybrid element made of glass fibers and resin-coated
cellulose fibers. The coated cellulose fibers give the element the strength
it needs (very omportant in Volkswagen applications, as we have learned),
while the glass fibers act as barbs to catch particles. New construction
techniques give the Fram Extra Guard filter the characteristics of both a
surface filter and a depth filter.
The result is an increase in single-pass efficiency from 92.4% in the
Wear Guard series to 96.3% in the Extra Guard Series, with no increase in
restrictiveness (both filters are rated only 3 psi pressure drop).
Project 924 may have been abused in the past, but from now on it gest
nothing but the best.