For a typical Kelisa (no modd):
Petronas gives more KM, but engine is somehow very noisy
Shell gives a smoother drive, quieter engine, and better aceleration
Esso/Mobil gives smooth drive but less KM and power compared to Petronas
BHP similar to EssoMobil but 1st few tanks, engine knocking appeared!
So, Shell is best for a spirited drive where u can zoom here, zoom there.. Petronas is for KM, while EssoMobil and BHP is for collecting points~
*tests done over 4 year period~

But the new shell super + economy formula didn't try yet~

Added on February 26, 2009, 10:56 pmQUOTE(vandetta @ Feb 26 2009, 01:20 AM)
If want to save $$$, buy the RM1.70 RON92 la bro

Not necessary~
Fuel is cheaper but is not as pure, so mileage may not be as good..
Btw, if u change stations regularly (Shell-->Mobil-->BHP-->Shell-->Petronas)..FC will be very very bad!
This post has been edited by jVIPERs2: Feb 26 2009, 10:56 PM