You will have to see the specification of your engine.
Normally turbo charged engines & high rev NA engines require
RON98.
Normal engines can take RON95 & 92. However for older
engines it is preferable to stick to 95 because of the wear &
tear. Because the chances of knocking is higher due to worn
ignition circuit together with the worn piston rings resulting in
compression lost.
Actually V-power is 98.Best Chem Pte Ltd sells racing fuel for
motorsport events. Those racing fuel comes in RON 120 - 140. Few
hundred bucks for a 20 litre tin. However the engine have to be
tuned to run such type of fuel. The ECU have to be remapped. It
normally applies to the Evos & the Rexes preparing for track
events at Sepang.
Back to the topic, I prefer Caltex because of the anti carbon
agent in the mixture. Better for your engine in the long run.
Comparing with Shell V-power, it is actually still 98 but the only
difference is in the anti sludging agent in the mixture. It
actually cleans up the fuel system. That's why you can feel the
different throttle response.