Do penguins have oil on their tails?

Penguins do not have oil glands and consequently do not have oil on their tails. The secretion of oil from glands is a feature in many types of birds, as they spread this on their feathers to maintain them and stay waterproof in water. However, penguins are unique as they have evolved without this feature, and hence, they do not have any oil on their tails or bodies.