cron job every 5 hours

[Dave]

Hello,
    I want to run an updater script, every 5 hours and x minutes. I thought 
to use:

minute 5 * * * root path/to/scriptname

but that looks like it only works once a day, i want it to go every 5 hours 
not justa at 5 in the monrning.
Thanks.
Dave.