Mac

Mac, nicknamed "Oily Diesel", is a Tar or Oil Diesel.

Mac came when Alternia The 3rd had completed to pull the Grand Express. He was chosen to pull Tar or Oil Wagons.

He sometimes pulls Tar Wagons, or Oil Wagons, because his favorite color is black.

His driver is Kanaya, Feferi, Equius, or Gamzee. When absent, Tavros or Nepeta drives him.

Episodes:

Season 1: Oil, Kanaya's Bad Day (cameo), and Feferi's Water Park Fun

Season 2: God Cat's Wriggling Day Ruined,

Hurry Hurry! Go Fast! Go Fast! (does not speak; cameo), The Crane (cameo), and Jug Up! (cameo)

Season 5 : All the episodes

Season 6: All the episodes except, Gamzee's Fossil

Season 9: Tavros, Mind Your Wheelchair (cameo), Tumble Down! (cameo), Class 553, and Iron Screws Up

Season 10: All the episodes