Motor noise

I was coming up at hill in my 2003 nissan xterra 4x4 auto and all the sudden for no reason it lost power then started to rattle and the oil light started flashing when I got to the you on level ground I shut it off and it wouldn't start back let set 4 or 5 minutes it started back up then started to rattle again I checked oil still full and clean what should I do to fix it or is it to late and need to replace it from start of rattling til I shut it off 3 no more than 4 minutes