I have a 06 chevy silverado 6.0 on start up the oil pressure is low 8-10 oil pressure and after a few minutes it starts to raise up. What could be causing this. It does this more often on cold days than on warm days. Any help at all would be appreciated.

What grade of oil are u using. Sounds like the pump is having a hard time when the oil is thick (cold). Or possible the pump is getting worn out. The oil should be 5w30. What u use in it?

If using 5w30 try switching to a synthetic. Synthetic oil flows better when cold.

I use 5w30 oil and the last time i got it changed I used synthetic oil and it didn't change it. I'm tearing it down and putting a oil pump in it. I figured it wouldn't hurt with it having 296000 miles on it.

Very well could be a bad pump. I have a line on a cheap 5.3 for my truck due to a bad pump.