What oil was the previous owner using?
U can use any 10w40 oil if your unsure what the previous owner was using
U could use fully synthetic oil but that would be a gamble if the previous owner was using mineral oil of e.g 10w40 or 10w50
So if the previous owner was using mineral oil use that if he was using fully synthetic use that.
If you dont know to be on the safe side use 10w40 grade oil.
U could buy mobil 2000 10w40,liqi molly mos2 10w40 its cost 4000rs for 4 litre, u could zinc too, havoline has 10w30 that could be used too. Shell has 10w40 too. Whatever you could find orginal.
You could get oil from honda they too have one mineral and one synthetic option. Mind u honda doesn't make their own oil.
If you opt for synthetic oil then every brand has many options. But the best price wise is shell helix ultra hx7 the blue bottle one. Its economical and gets thr job done. You could go with fancier options from liqi moly likr 5w30 and other but they cost more than shell.
Shell is readily available and cheap as compared to other options.