Is the chain making a noise? There really isn't any manufacter recommendation. Make sure you change the oil regularly. I personally would use synthetic lubricant, Amsoil or Mobil One. I do know what I'm talking about. I have 40+ years experience.
I have been an Amsoil dealer for 30+ years. if you follow Amsoils recommended lubricant change interval it is less expensive than any other oil. If your interested in learning more contact me at firstname.lastname@example.org