While he was known for using various effects, the Tube Screamer is considered the cornerstone of his tone on this track. It gives the signature "gainy" and "warm" feel to his guitar sound, which complements his signature bluesy style.
Although it is generally accepted that he used a Tube Screamer, the specific model and its settings remain a matter of speculation among fans and guitarists. Some believe he used an early 80s version of the pedal, while others speculate that it was a slightly modified one. Regardless of the specifics, the Tube Screamer is undeniably a key element in the "The Loner" sound.