Can I use in my Nomad II.
This is the best oil for diana 350 Magnum?
Best oil for what part of the gun? What are you trying to lubricate?
can this be applied to a pcp fill probe so it goes inside the cylinder when i pump it to prevent corrosion without the possibility of oil combustion causing an air reservoir explosion?
Yes, but the Hill grease will be better and last longer: Hill Hand Pump NLGI 2...
is this oil safe to use on N/P break Barrell rifles like the Benjamin trail N/P rifle
this ok for pcp air rifles if not what do you recommend?
If you are looking to lubricate o-rings I would recommend using some silicone grease. This would not be my first choice. Check out the Hill Pump Silicone grease.