I bought a used 2007 2500 with LT 2 motor when start up it is 10-15 psi oil pressure it also has a slight tick to motor but seems to go away when warms up when warm seems to be about20-30 is this OK j

I believe there is a screen under the oil pressure sending unit that will get plugged up not letting the sending unit to read properly. You have to take out the sending unit and fish out the screen & clean. Who ever checks this out might as well replace the sending unit since it is out.

As far as the lifter tic, as tennisshoes says it needs to be checked over, I just wanted to add that this is common on Chevy's, a lot of the time you can adjust the rocker arm to get the tic out. All rocker arms should be checked for proper adjustment.

depending on miles? you could seafoam the motor a couple times and if higher miles try a thicker oil. could be bad oil pump. or just dirty. try seafoam first which cleans inside motor good. youtube it, it works