Because oil to be filtered passes through the first filter member 42a before passing through the second filter member 42b, {HEAD ~ the first filter member} will ordinarily accumulate {TAIL ~ particulates} at a faster rate and become clogged prior to the second filter member 
Because oil to be filtered passes through the first filter member 42a before passing through the second filter member 42b , { HEAD ~ the first filter member } will ordinarily accumulate { TAIL ~ particulates } at a faster rate and become clogged prior to the second filter member
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH