Here is how you measure the standby current:

Place the meter in series with the ground cable (as you have done).
REMOVE KEY, close doors, and wait at least two minutes. DO NOT CONCERN YOURSELF with the current reading for two minutes!)

Specification is less than 55 mA - that is, less than .055 amp.

Fuse 8 is battery feed to the radio, if you have that much current and fuse 8 makes it go away, take the radio out of the dash and drive over it with your lawnmower. Then, throw it away and go buy a new one.