I recommend Salon de Master Ssyung Ssyung Hair Serum. It has a lightweight texture. It isn't a well-known brand, but it's a product recommended by a hair salon. My mom and I are using it together because it's said to help alleviate hair loss symptoms, and the texture is especially good for summer use.
I think this is perfect. I usually don't reach for oils because they leave my hands feeling sticky and uncomfortable after use. I recommend this product!