If you want to maintain warranty then you are stuck with suzuki oil SG / SM 10w40, as mentioned on the sticker inside your bonnet and in the warranty booklet. Any other brand/viscosity will render your warranty void. Have a written confirmation from an authorized person before using any other viscosity of even suzuki oil, because they might use it against you if something goes wrong and u have to claim warranty.
On the other hand if you dont trust/like ur local suzuki dealership then there are many good brands like liqui moly, zic, caltex (havoline) ........ Just search Pakwheels forums and u will find heaps n heaps of information.
I, personally, am sticking with the warranty option and suzuki ultimate oil 10w40 SM. BTW suzuki oils are manufactured by Total for Pak Suzuki.