Some years ago, I had a number of very interesting
conversations with a guy who had started in business making
air filters. He seemed to have made a comfortable pile of
money in the process making filters where the demand was too
small for ful scale production and he did a lot of
own-branding work for the big names. Then he turned his
attention to diesel fuel filters and finally engine oil
filters with a wide range of application and fit.
I've since bounced some of his thoughts and views off some
of the 'big boys' and broadly they all seem to stack up to
the same thing.
The filter media (paper) is the critical factor. This is
obviously available and there's no reason why oil filters
should not have a media capable of trapping particles down
to about 10 microns which I'm told is about the size of one
grain of fine sand. A filter capable of protecting down to
2-3 microns (about the same size of one grain of talcum
powder) could be manufactured and you can go much finer than
that and use a paper in a full flow filter that will trap
particles to about 1/10th of a micron - but the unit price
then goes up quite substantially. A number of conflicts of
interest enter the scene here:
1. Many filter manufacturers avoid using finer media to
promote 'super filters' because this will virtually demand
additional marketing expense. They are concerned that
publicity indicating a filter will keep oil cleaner for
longer will inevitably lead to even less frequent oil
changes. This could sour relationships with the vehicle
manufacturers for whom many of the filter manufacturers
supply as OE.
2. A higher quality filter (with finer media quality) runs
the risk of becoming more choked and this increases loadings
on the oil pump to keep the stuff flowing. If the pump
fails, who will Joe Public blame? Probably the car
manufacturer? How many private owners (even us) regualrly
take a hacksaw to a filter we've just removed to look inside
it? Even if we did, do the majority of us without extensive
laboratory facilities in a corner of the workroom have the
knowledge to tell us whether the filter is doing a good,
indifferent or bad job?
3 Too many people feel that "dirty oil is no good" and this
is an argument the oil companies will enthusiastically
support. As we all know, 'dirty oil' can be used with
confidence but for how long and to what contamination level?
Modern oils have additives that wrap pollutants so they
cause minimal damage - but there is a limit. Its not just
the 'lumps' of stuff floating around that oil circuit which
cause damage. There are the filter resistant elements such
as acids and entirely transparent pollutants that are just
as damaging and that very few (if any) commercially
available filters will safely trap.
The bottom line surely has to be regular changes of oil and
filter. In both cases, buy the best you can afford and look
after both while its in your engine. If I could afford it,
I'd imitate the taxi drivers in the Middle East who usually
change oil and filter DAILY but they have the advantage of
living rather close to the source of the oil in the first
place. This probably goes some way to explaining why so many
of the engines enjoying such treatment seem to cover quite
amazingly high mileages.
Jonmac
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