Roy Newburn borrowed money and bought a $49,000 truck from Treadwell Ford. A few months later, the truck developed transmission problems. Newburn learned that the truck had 170,000 more miles on it than the odometer indicated. The company admitted the mileage error and promised to install a new transmission for free. Treadwell did install the new transmission, but when Newburn came to pick up the truck, Treadwell demanded that he sign a general release absolving the dealership of any claims based on the inaccurate mileage. Treadwell refused to turn over the truck until Newburn finally signed. The truck broke down again, and delays cost Newburn so much income that he fell behind on his loan payments and lost the truck. He sued Treadwell, which defended based on the release. Is the release valid?