Which o-ring to use, RED or BLUE?

[Hart_Rod]

I'm changing the oil pan/pick-up tube on my 6.2 2013 Camaro SS engine to a 2007 Cadillac CTSV oil pan/pick-up tube. The Camaro pick-up tube has a RED o-ring and the Cadillac pick-up tube has a BLUE o-ring. I tried them both and they both fit, but the red O-ring "seems" to fit better. I need to make sure I have the correct one in there because I don't want to have to change it out after I install the engine (or even worse damage the engine). Any suggestion would be helpful. TIA.

EDIT: the 6.2 was a AFM/VVT engine but I deleted both of those internally. The CTSV pan does not have the oil bypass like the Camaro pan does. Not sure if this makes a difference, but like I said I don't want to have to do this again.....