Preheat the oven to 350°F (175°C). Line two baking sheets with parchment paper.
In a medium bowl, whisk together the rolled oats, all-purpose flour, baking soda, ground cinnamon, and salt until well combined.
In a large bowl, combine the granulated sugar, light brown sugar, and vegetable oil. Whisk until smooth.
Add the egg and vanilla extract to the sugar and oil mixture. Whisk until fully incorporated.
Gradually add the dry ingredients to the wet ingredients, stirring with a wooden spoon or spatula until just combined.
Fold in the raisins evenly throughout the dough.
Using a tablespoon or cookie scoop, drop rounded spoonfuls of dough onto the prepared baking sheets, spacing them about 2 inches apart.
Bake in the preheated oven for 10 to 12 minutes, or until the edges are golden and the centers are set.
Remove the cookies from the oven and allow them to cool on the baking sheets for 5 minutes.
Transfer the cookies to a wire rack to cool completely before serving.