Your oil looks pretty black for an oil change of a few weeks ago
Edit: If you don't know what oil is in it, don't just go topping it up with something else, change the whole lot inc filter.
+1. Your oil to me doesn't really look all that new as you might expect with just having an oil change a few weeks ago.
I'd probably do what ts743 has suggested and just do an oil change ~ that way you know it's definitely been done and done right.
The oil a lot of us Zed owners use is 5W30 btw ~ I personally use Fuchs ProS but Motuls another good oil & I'm sure others have their own recommendations.