...where r you on 1-20? I've pulled pretty heavy trailers all up/down I-20 but can't say I remember anything so steep I had to shift to 3rd gear, but its not out of the question depending on if I could maintain good speed (60mph plus) or maybe I had to brake for traffic. These motors are solid but def aren't know for pulling power. You probably know this already but don't tow any in 5th gear...keep it in 4th. Blew out my trans that way...