I have a deep cycle dry cell odysse battery and a regular interstate battery and my question is can I run them together In parallel? Will it hurt either of the two batteries?

Yes, but I would disconnect them if you're going to leave it for any length of time.

Sweet. Thanks for the help.

that shouldn't be a problem because they are both 12 volt and the vehicle is a 12 volt system

Yeah the reason I was asking was I am running an Oasis compressor and it pulls alot of amps at load and they told me to run the deep cycle battery and I had just baught the othe rbattery and didnt want it to go to waist. Thanks for the help guys

that shouldn't be a problem because they are both 12 volt and the vehicle is a 12 volt system

That is not entirely true.

If the batteries are not of similar age and type, and not kept at the exact same state of charge, they will discharge each other through heat as one battery tries to charge the other.

I usually disconnect mine when I leave it even though my batteries are both the same. I left them connected for two weeks recently and they didn't dischcarge each other, though.