Given that it is a Gas Turbine at 180 Deg C you will require Kalrez or Isolast that is less expensive. I suggest you contact you local distributor and provide full details of the duty conditions. Isolast web site is:
http://www.polymersealing.us/wlb_global.htm?wlb=17
What grade of o' ring are you using, grade of oil and temperature? EPDM will disintergrate very quickly in oil. Viton can be used up to 180 Deg C max. Above that you will require Kalrez or Isolast.