Dirty or contaminated hydraulic oil can damage internal components and void the manufacturer’s warranty. JLG recommendations for hydraulic oil cleanliness levels are based on the three-digit ISO code for 4 micron/6 micron/14 micron particle sizes found in 1 ml of fluid (reference ISO 4406:199(E)). The acceptable level is 19/17/14 or below; anything higher requires system cleaning and filter replacement. (It’s important to note that the human eye can only distinguish particles down to 40 microns – smaller particles that are sampled are not visible.)

Reference the JLG Service Manual for the appropriate maintenance intervals based on the hours of operation. If your equipment is exposed to extremely dirty or hostile conditions, more frequent service may be required. Always use original JLG filters to assure necessary filtration requirements are met.