I have an '05 Silverado 1500 Z71 with the 5.3 liter and I've noticed that lately my oil pressure after start up has dropped to about 25 psi from its normal 40 psi that it usually runs at. Does anyone know if this could possibly be the same issue as mentioned in this post or does anyone have any other insight on the situation? Thanks for everyones help... I just found this forum and I can't wait to use to it more often!