Differential noise

Had received recall for "rear axle pinion nut" Had this recall done by Dodge dealership on 8/1/2016. Recently the differential is make noise. When I inspected it there was little to gear oil in differential housing. I filled it up and noise is still occurring.
Wanted to know if this recall requires drain/refill of gear oil and the lack of gear oil would have caused damage to diff and that is the noise?

Thanks