General LSX Automobile Discussion - Low oil press. on my 5.3 z71

I bought my truck back in january and as long as ive owned it the oil pressure has stayed low, and by low i mean that it will sometimes idle at about 5-10 psi when hot and sunny outside.under accelleration at most it will so 40 psi if i am lucky. I know this isnt normal i know a few different people with the same truck and theirs will idol when warm at 40 psi. The truck runs great and as it should and it has about 135,000 on it. Could my oil pump already be going out? I dont really want to replace it but then i dont want to seriously mess up the motor as it should still have plenty of miles left in it.

Could be a lot of different things...bad pressure sender, bad pump, bad bearings, wrong oil weight (although I don't think it would make that big of a difference). Easiest thing to do to start with is hook up a manual gauge and make sure that it's not the sender or cluster that is reading wrong.

Does it fluctuate also depending on throttle position? Or just based on RPM?

yeah it will rise under wot and stays right above 20 on the highway. where can i find a manual gauge and how do they work?