Syntium 3000 is only available if you order from petrosa (~R80/l) and it is quite a process. It is also cheaper if you can buy it from a BMW dealer, but I'm not sure if they will sell it to you, since they buy a drum, so maybe if you take your own container. (R6.2/100ml ex vat)
Shell Helix Ultra Extra might be the easiest to get hold of, or Mobil 1 or Liqui Moly