These seven items are excerpted from a checklist in The Practical Handbook of Machinery Lubrication:

Are existing full-flow filters capable of meeting the equipment manufacturer's specifications or have these filters been replaced with less expensive jobber filters, whose quality and efficiency ratings may be questionable?

Are all lubricants prefiltered before being added to the system?

Are all breathers, filter bypass indicators, external seals and other contamination control devices operating properly, and are they inspected regularly and serviced when necessary?

Are only top-quality, specified fluids and lubricants used and are they stored properly in a clean environment?

Are all leaks repaired as quickly as possible, particularly those in dirty environments?

Is the entire system thoroughly flushed and serviced completely, after any major component failure and subsequent replacement is carried out?

When flushing is carried out, particularly on a hydraulic system, is the reservoir opened and thoroughly cleaned by hand?

More about The Practical Handbook of Machinery Lubrication

On both hydraulic and lube oil systems, most suppliers typically size filter housings near their upper volume (flow rate) limit. Filter housings should be selected with ample flow capacity at the required micron filtration, oil viscosity and any potential operation surge. This will provide proper filtration/component protection under various circumstances, such as component wear, varying oil temperature and changes in oil flow rates and pressure. For hydraulic circuits, filter housings are sized by the information in a product brochure. This practice, if used in lube system design, will result in undersized housings, poor element service life, excessive flows though the element and operating expenses higher than expected. Lube oil, given higher viscosity ranges, may be 25 times heavier at startup, and seven times heavier than oil viscosity and any potential surge condition. Read the entire story.

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