Preheat the oven to 180°C (or 350°F). Line a muffin tin with 12 papers; set aside.
Mix oil and sugar with an electric mixer. Add eggs, one at a time, beating well after each addition. Add vanilla and mix until combined.
Then add the flour, salt and baking powder and mix until just combined - no more otherwise the muffins will be tough!
Add the milk
Fold in the blueberries by hand. You could reserve a few to place on the top if you are so inclined.
Fill each paper liner about 2/3rds full.
Bake for 30-35 minutes, or until the center is set.
Remove from the oven and let cool for 10 minutes before transferring to a wire rack to cool completely.
Store in a container for up to 4 days at room temperature.