Considering you bought it used, look to see if it has the plastic or aluminum fitting on the manifold side of the separator. The early ones have a plastic fitting (the straight one) on the manifold side that often breaks after time. The 90 deg fitting is also plastic but that one has not had any issues. If the fitting is aluminum you're good to go. If it is plastic, contact JLT and they will send you the new upgraded fitting.
I've also noticed that when the separator hoses get hot and relax, the separator rests on the radiator hose. So I tie wrapped a piece of rubber there for the separator to rest on.
I collect about 1 tablespoon of oil per 1K miles in my separator.