Try the 6th quart and see if it helps.
I run Valvoline Racing 30 weight in my 292. But I live in a hot climate. [Southern Arizona] In winter I have run 20W-50.
My Oil Pressure Gauge reads about 40 PSI.
I/I #4101
'71 GMC Jimmy 350, sm465, np205,3.73 posi.
'68 C/10 Stepside 292 (.030 over) Offy Intake, 500 CFM AFB,Clif headers, sm465, 3.73 posi.
'67 K/10 454 project.
'72 K/5 rolling frame project.
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