I got a 350 tbi in k2500 and when in a cold start it show its a 35 or so psi.When it gets hot its at like 15 _25 psi,the oil it has in it is 5w 20 penziol junk to me .What could be the problem with low oil pressure guage,bearings ,oil pump, oil screen, i have no idea my uncle said it should be...