Any sunscreen with SPF 15 and above is suitable for Indian skin . Since you have oily skin, you may use a gel based sunscreen. Apply around 1.5 gm all over the face before 9.30 am . If you take sunscreen on your finger tip till the first crease or line , it is 0.5 gm . 3 such units are needed for whole face. If you find it oily, you may apply powder over sunscreen. Repeat sunscreen between 1 to 2 pm and keep till 4 pm. Use cap, helmet or umbrella between 10 am to 4 pm - when UV light is maximum in sunlight.