Melchior

If it is feared that my syncros are a little worn, should I stick with dino or can I use synthetic? The last tranny oil change that I did revealed some small metal shavings. This was about 6months ago and I haven't noticed anything wrong with the tranny; put dino in the last time. However, now my reverse gear makes a slight noise when it is engaged as well as when powering the car in reverse. Any thoughts?
Redline, Swepco, or use heavier weight dino like 80W140?