I use BP or Caltex 91 octane almost all the time.  I found that when I used BP or Caltex I wasn't having to use a fuel injector cleaner every few months.

Anyone know if the fuel companies really do put their own additives in 100% of the time or is this skipped sometimes?

Which brand has the best additives?

From what I have read these additives are put into the tankers at the bulk distribution depots.   In Britain, from what I have read, the cheaper fuel from supermarkets etc may not have any additives & really is lower quality than the name brands.  It seems to be harder to find any information about this re. NZ, so any comments would be welcome!