Im sorry for being away and not responding to your queries. Ive been pre-occupied with other things and considering that i sold my bike, i havent been checking the forum lately.
Oil: Please read the oil requirement in the TNT25 booklet and stick with one brand. Do not change the brand of oil that you are using as it could damage the engine and reduce its life
Petrol. Minimum requirement for optimal performance is ron95, as stated on the bike. Higher RON petrol is always better and since it is an EFI engine, i highly recommend atleast RON95