means for directing said intermingled oil and {HEAD ~ coolant} back to said {TAIL ~ coolant tank} 
back to
means for directing said intermingled oil and { HEAD ~ coolant } back to said { TAIL ~ coolant tank }
OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD REL REL OTH TAIL TAIL TAIL TAIL TAIL TAIL