79 Chevy 350 V8 that has been rebuilt warm idle oil pressure is 5 to 10 psi will thicker oil help I have 10w40 in it now the oil light doesn't come on but does work?

10 lbs. of oil pressure at an idle is not uncommon for a 350 if the idle is low . what does it do at 30 mph. or more ? that is where you should be concerned. if the pressure is around 40-50 lbs. at 50 mph. it's ok.