Fordhead, do you really find any difference between Shell Optimax and BP Ultimate??
You see, these fuels are one and the same. Actually, they are both Shell Optimax. Your BP Ultimate comes from Geelong.
This is from the BP website.
A particular feature of the Australian oil industry is the practice of refinery exchange, in which refining companies exchange products in various locations to minimise distribution costs. For example, BP supplies other companies in Perth and Brisbane and in return is supplied with product in Melbourne, Sydney and Tasmania.
That is, BP and Shell have a sharing arrangement.
So all you people in Melbourne and Sydney, who somehow find BP Ultimate better than Shell Optimax could possibly be victims of dodgy servos, but certainly not dodgy fuel from one manufacturer because it is the same fuel, BP and Shell trucks get it from the same refinery
Brissy/Perth people will find their Shell Optimax is BP Ultimate.
This sharing arrangement has been around for ages. My sister worked for Mobil, and told me their 98 RON premium was trucked from the Adelaide refinery which was responsible for the greater gap between 91 RON and 98, but I'm unsure if this is still the case for Mobil. It gave Shell/BP an excuse to raise their 98 RON fuel prices with a similar gap.