I've had my 33 for just over 2 years now, done 16k miles in it and I've changed the oil 11 times so far. May seem excessive but I never do more than 2 track days on the same oil and never more than 2k miles without changing it. I always use Mobil 1 Motorsport. I've also changed all the transmission oils and fluids twice in that time along with 2 sets of HKS Power Flow filters.
I'd agree - preventative maintenance and all that. I'd actually been considering Castrol VMX80 or one of the Motul oils for the gearbox. Do you know the capacities (roughly) of the 'box and tranfer case?
The gearbox and diffs take about 6 litres from memory and I think the transfer box takes over a litre. Sorry not be precise but I've got some of both left over. I guess Gary or Shin or Gazmo would know the exact amounts involved.
Seems like its different strokes for different folks really. I think that I will stick to a 6000mile schedule (which is still cheaper than the Mak I had - every 4500 miles at £300 a go!) unless I plan on doing any trackdays.