tedinindy

5 qts of oil including filter is correct for the 5.7. You've got good oil pressure, it is right where it should be for that engine in very good condition. Different oil brands or wieght ( 5w-30, 10w-30, 10w-40, etc..) won't make the pressure vary all that much. The pressure will drop slowly over time as internal engine componentswear. Really low pressure (<15 at 2000 rpm)on a fully warmed up engine usually means worn crank bearings and piston rings. A major rebuild or short block would be needed. Regular oil changes with quality oilhelps minimize internal engine wear, and oil pressure loss.My98 silverado with a 5.7 vortec when it was new, had oil pressureof 50 - 55 psi warm at 2000 rpm, 70 - 80 psi cold at startup.I changed theoil every 3000 miles and alwaysuse 4 qts 5w-30 valvoline duralube synthetic blendand 1 qt lucas heavy oil stabilizer.I'm at225,000 mileshaving done nothing but scheduled maintenence. The oil pressure fully warm at 2000 rpm is around35 psi.Coldpressure around50psi. I'm told by my local Chevy service departmentanything 20 psi or > fully warm at 2000 rpm is within safe operating oil pressure specifications. Hope this helps.

northey87