hi am new here......i have 1996 chevy blazer 4.3 cpi 4x4 w 203,000 and the oil presser is at 40 psi when cold start up and when fully warm up it goes to 20 psi and when stop its even lower like 2 psi and the gag comes on and when driving it gose to 20 psi and it has a slight knocking sound ....had a blown head casket from the person that i bought it from fix it temply w bars stop leak ......so what am asking is would zmax help build up oil presser i am trying to get thur winter with it and spring will be pulling the motor w gd one plase help w any possable idas thanks or if need more info will get it