Fortigate and Syslog Question

-Fortigate 300D

-Firmware 5.2.6 build 711

Logs are being sent to a Syslog server, and appear to be Information severity/priority level. This is way too much logging. I would like to drop this down to Notification or Warning level. In the GUI or CLI, I don't see a way to adjust the level, only enable/disable "Endpoint Event," "Router Activity Event, "VPN Activity event" and so on for the VDOMs.  How can the logging level for Syslogs on the Fortigate be adjusted, or is it a matter of filtering what gets logged at the Syslog server?