Here's some good documentation from Cisco about DSCP: http://www.cisco.com/en/US/docs/ios-xml/ios/qos_dfsrv/configuration/12-4t/qos-dfsrv.html.
There may very well be something I'm missing, so hopefully someone else can verify this (not a CCIE, yet), but the important bit to know is how these DSCP values map to the binary values, and what AF (Assured Forwarding) is.
DSCP 0 (decimal value 0) would be 000000 in binary. For AF, you can see that document for more details, but AF13 would be 001110, which is 14 in decimal.
However, it does not go directly off of the decimal value. If you do not specify any other configurations there, it will use the defaults. You can find these in this table: http://www.cisco.com/en/US/docs/ios/12_2/qos/command/reference/qrfcmd7.html#wp1070240.
So, DSCP 0 (default in that table) would be more likely to be dropped in that the threshold where it could be dropped begins at 20% vs 24% for AF13.