When it's due its oil change it will say service due in so many miles and so many days, your best off topping it up, i check my oil level each week, it only takes a second with loss of oil pressure and you've got a big bill, i keep mine on the maximum, reducing the risk of oil surge and oil starvation.
5w30 use good stuff (castrol, shell).
Give your car all the maintenance it needs, all the maintenance it wants and a little bit more to keep it happy.