170 Dart compression advise???? please??

Did you check your Valve lash ? I am a rookie and the tec's here don't mind at all to help us out OLD Dart, If the valves are not closing or opening all the way your compression will not be where it should be, and when you added the oil it took up room in the cylinder and brought your compression up.
Have you ever set valves before on a slant 6 ??