Magnetic plugs and chip collectors are often used in system tanks and return lines. They can provide a quick picture of past and ongoing active wear. If they are inspected at uniform time intervals, the rate of wear can be estimated. Debris particles can occasionally be transferred to patches and slides for microscope examination.

One of the advantages of using magnetic chip collectors is the fact that the particles are usually presented in the original shape and size. Otherwise, these particles tend to get reworked by the moving elements, crushing them into smaller unidentifiable sizes.

Always ensure that disconnected hoses are capped while maintenance is taking place. It is surprising how much debris can enter an open pipe. This will find its way into the system in short order, causing accelerated wear.

"I've heard that the addition of by-pass filters offer advantages over just full-flow filters on diesel engines. What are these advantages?"

Some solid contaminants (dirt, wear particles, etc.) lead to abrasion and wear (rings, liners, cam, bearings, etc). Other contaminants (soot, sludge, oxide insolubles, glycolic compounds, etc.) can contribute to deposition formation in the combustion zone (crown land, ring lands, skirt) and valve area (valve seats/guides) of the engine.

These deposits can also contribute to wear and combustion efficiency problems with engines. Recent studies on the contaminant sensitivity of engines have found all of these solid contaminants to be important to engine reliability and efficient operation (relating to emissions, fuel economy, oil consumption, etc.). These contaminants are typically suspended in crankcase lubricants in sizes ranging from submicron to more than 100 microns.

Typically the very best full-flow filters exhibit a capture efficiency of 50 percent at particle sizes 10-microns and above. Smaller soot suspension and polar insolubles that can also cause wear and deposits are not controlled by these full flow filters effectively. For this reason, compressed cellulose depth media used as by-pass filters can offer benefits in removing fine organic and inorganic particles. In combination with full- flow filters the benefits can be lower wear, lower oil consumption, higher combustion efficiency, and longer oil life. There are a variety of by-pass filters on the market including centrifugal separators.

Things to consider when buying a by-pass filter include pressure vs. flow (P-Q), Beta or capture efficiency at say 3 microns, 6 microns and 15 microns, and dirt-holding capacity. If the filter supplier has tested its by-pass filter to standard procedures such as SAE J1858, ISO 4548 or ISO 16889 this information would be available.

By-pass filters also increase the total volume of oil used by the engine. This means that more oil additives are available as well as fluid volume to dilute the concentration of contaminants.