My buggy (Hyper 7 PBS Pro) goes to about 1-2 race meets a month, don't bash it much at home so its not getting a great deal of use.
1 guy at my club rebuilds his Mugen after each meeting with fresh oil for both the diffs and the shocks but he has money to burn, another guy who won the A grade championship last year with a Hyper 8 said only once a season unless it leaks, while the track owner said just check it every 6 months, if it is still clear and topped up just leave it...

?? whats best?