Sam’s grey sweater looks soft and comfortable.
In Route 666 (1x13), Sam is wearing the sweater at the gas station at the start of the episode when Dean gets checks his messages, and continues to wear it until after tea with Cassie and her mom. He wears it again when it’s time to say goodbye.
In Playthings (2x11), Sam is wearing it at the beginning of the episode while he tries to find Ava, and tells Dean about the possible job at the inn.
In Sex and Violence (4x13), the sweater appears again after a long absence. Sam is wearing it at the beginning of the episode, while he talks to Ruby when Dean is sleeping.