Ok, just put in a used motor, got it all together, start it up, and let it run to circulate fluids, but the oil pressure guage drops then goes back up, then drops again then goes back up again, until it starts to warm up then it'll stay up, but I'm just concerned about this since it took me nearly 3 months to do a motor swap while on unemployment.

 

Change the oil pressure sensor.

 

This that the one right by the oil filter?

 

Yes.

 

Ok cool, i'll just pull the one from my old motor and put it in. Will I lose oil when I do this?

 

you'll lose very little oil. thisd was the problem with my 4.6. Changed the sensor and no issue after that.