Cleaning the oil
Should your fleet start fitting bypass filters?
Bypass filters have long been the standard way of cleaning engine oil. But in recent years, the marketplace has seen new technologies from upstart companies challenging conventional wisdom and claiming their filters will allow fleets to preserve or even lengthen engine life while extending oil change intervals.
While still a gray area, these radical approaches to managing change intervals gradually are gaining respectability. The Technology & Maintenance Council has endorsed a procedure for fitting bypass filters, which includes extending oil change intervals and keeping tabs on oil condition with regular oil analysis.
“Supplemental filtration systems will help equipment users maintain acceptable oil quality for an extended period of time as compared to operation without such a system,” TMC’s RP 359 reads. But how long can oil filtered down to tiny micron levels safely be left in an engine?
A bypass filter takes a limited amount of oil and filters it, then returns it to the sump. “This maintains a cleaner sump,” says Paul Bandoly, manager of technical services and customer training for Wix. “The bypass filter is like slow-pitch softball compared to a full-flow filter. It works at a much slower velocity of fluid flow, so it can catch much smaller contaminants. This is possible because it has a much tighter matrix.” Such a tight matrix would restrict flow too much for use in a full-flow filter, depriving the engine of oil or causing the filter medium to be bypassed.
