As I stated previously - I use Amsoil 10W30 and burn less than 0.25 qt every 5,000 miles.
If you don't want to wait to change it (and I don't recommend you do) and don't have an Amsoil dealer near you (you can use the web to search for one near you), Mobil 1 Extended Performance or Pennzoil Platinum synthetic are okay oils. Make sure you get the Honda PCX filter which is specifically designed for the S2000. The standard Honda filter will fit on the S2000, but will likely restrict oil flow if used. It's a very skinny filter, barely wider than the gasket. The PCX filter is much fatter.
I would get an oil sample kit and sample the oil that was used to see what they put in.

 

did you check the oil after driving it? A lot of oil could have still been in the head.

 

i use elf 5w-40 and i don't burn n e thing, took it up to the drag strip too and checked before and after and it was still at the full line

 

I just bought and 02 and have driven it about 2,000 miles. I've had to put 1.5 qts in it so far. I can't find any leaks. I bought it from a Toyota dealership and I know they changed it before I bought it. I'm not sure what weight they used. But, I've added Castrol GTX 10w30. This consumption seems real high to me.