Those are both redline products, and you've basically described what I'm using anyway (in terms of oil specs, ignoring brand).
Busty, I don't expect much to change really, my car has done < 40k kms and the old gearbox oil was still in good condition when I drained it this arvo. Preventative maintenance, really - at least now I know it has good oil in it and I won't have to worry about it for another 3-4 years!
Couldn't get the bastard diff plugs undone though, I'll need to get the car on a hoist so I can have a proper swing at it. The gearbox plugs came undone with just a ratchet