Hey OP,
There was a very good thread on this few months back with alot of information, please use search Button next time.
But ill sum it up for you. Winter is kinda correct in his statement. That there are Certain refinerys which varry state by state. Eg, in QLD BP is the refiner so all the fuels will pass through BP Refinery where they add the additives as required by shell/mobil/Caltex and what not.
But thats not the main issue thats going to determin how good the fuel is when you get it. Cos these companies are very good and strict in what they do.
There are many factors that effect how good is the fuel that you pour into your tank.
How long the fuel as been sitting in the tanks at the petrol station as 98 fuel is highly evaporative this is a major factor "freshness of the fuel"
How old the servo is = more rust in tanks and what not from over the years of operating.
Buying from a well established brand over them lone wolfers
And ofcourse the condition of your car.
Fuel filters are normally over looked in servicing this also plays a big role on the quality of the fuel that gets injected in your motor.
Using additives like ocatane boosters or what not (im against these as i dont see whats the point when you can special order 102RON fuels from alot of outlets)
I guess you may see the picture. My personal Choice is Vpower, in my em1 gets me 350km if i fang the tank away. 550kmish as soon as the light turns on when driven civilised. If no shell in my current location then BP is my next choice as I'm so what a fan of engineering and they have the most advanced refiners in the world
.
My lil brother is currently on Caltex 98 and his seeing very similar KM's on his ej6.
Yes i wrote a bibble i hope this helps you decide where to get fuel from. All the 98 is very similar (has they are all 98 octane change chemically) Just alot of variations that come into play. So dont relay on the forums people saying this is good and what not. As you may realise now the Shell down the road from yours might have fuel thats approx a week old compared to the BP who just got refilled and what not.
http://roadrider.com.au/gear-reviews/the-fuel-truth
Heres a good write up OP.
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