We use a zinc free hydraulic oil in my facility and in several of the systems we often find as we change filters that the oil has jelled. If this jell condition is severe the filters will clog prematurely. If the jelled substance is removed from the hyrdraulic system it will return to oil. The oil supplier has taken many samples and each time the results are inconclusive in that nothing chemically is out of balance.
Has anyone else seen this with zinc free products? I'm puzzled.