"18 lb oz" is not a complete mathematical expression or a standard unit of measurement. It's unclear what you're asking for.

To help me understand your question, please clarify:

* Are you asking to convert 18 pounds to ounces?

* Are you asking to add 18 pounds and a certain number of ounces?

* Are you asking something else entirely?

Please provide more context so I can give you the correct answer.