What la you guys.... No one actually took out the fuel and do stupid test on it at all. At least on my part i can tell you Shell & Petronas are almost the same fuel for all i care. Both these fuels have very aggressive detergents. On a very old car like mine where i can easily service my engine as needed, the fuel filter gets clogged easily from dirt/ particles with either Shell or Petronas. These 2 fuels have a record of leaving me stranded for fuel starvation problem due to clogged fuel filter. Seriously i do not have that problem with Petron.

On power output it is debatable. It is all the same with maybe only 0.1HP gains or loss between them on dyno excluding tuning.