"I Ride an Old Paint" is a traditional American cowboy song, collected and published in 1927 by Carl Sandburg in his American Songbag. NOTE: If the song has lyrics about leaving Cheyenne then it's "Goodbye Old Paint".
[Verse One] I ride an old paint, I lead an old Dan I'm off to Montan' for to throw the hooley ann They feed in the coulees, they water in the draw Their tails are all matted, their backs are all raw [Chorus] Ride around, little dogies Ride around them slow For the fiery and snuffy are a-rarin’ to go
NOTE: There is a different cowboy song called Goodbye Old Paint and both Works can have performances titled "Old Paint" that will typically be credited as traditional, so without audio of the performance it will be difficult to assign them. However, the 1928 Goodbye Old Paint by Harry McClintock has elements of both songs so they may actually have common origins.
If the song has lyrics about leaving Cheyenne then it's "Goodbye Old Paint".