Here is more info from:
http://www.oilguard.com/side_menu/bypass_filtration/bypass_intro.php
The two most important points to understand about oil filtration and engine protection:
Oil does not wear out – it gets dirty.
According to studies – 90% of engine wear is caused by dirty or "contaminated" oil.
What exactly is contamination and how does it enter an engine’s oil system?
There are four main types of harmful contamination that can enter your engine’s oil system. For an in-depth description of each type, click on a link.
Engine Wear (metal particles)
Sulfuric Acid (soot and water combined)
Environmental Dust (caused by a worn air cleaner)
Fuel (dilution)
Standard Filters versus the OilGuard Bypass Filtration System
Standard engine filters, also known as full-flow filters, are incapable of maintaining oil purity at a level that prevents most engine wear. To compensate for this weakness, manufacturers recommend an oil change every 3,000-4,000 miles.
The basic job of a standard full flow filter is to trap large contamination particles ranging in size from 15-40 microns, while at the same time allowing 7-10 gallons of oil to pass through the filter per minute. The most damaging contamination particles however are not in the 15-40 micron range, but in the smaller 5-15 micron range. Just for reference a human hair is 100 microns. Particles in this smaller range get wedged between moving engine parts, causing friction, resulting in engine wear.
To effectively remove these smaller damaging particles and to guard against engine wear, a bypass filter must be used. OilGuard’s patented bypass filtration system removes contamination particles as small as 1 micron, thereby providing an engine with four main benefits.
Cleaner Oil
Reduced Wear
Longer Engine Life
Extended Oil Change Intervals
[ December 25, 2002, 03:49 PM: Message edited by: pedaltothemetal ]