Hay brendan
I thought id put in my 2 bobs worth.... Definately right 5000km is the go, not 10000kms. Rb engines have a realy small pick up in the sump so it gets cloged realy easily and thats the last thing you want with an rb. I always replace my filter every 5000 with the oil change. for 8-10 bucks its not realy going to break the budget. I run genuine nissan 7.5/30w, its pretty thin when cold and hot. Thats what you want with a high reving turbo rb. Its the same oil as they come out with from the factory so its been designed to run with nissan engines. One added bonus to its only $40. I Recomend it!!!!!!
Over and out
Stu