Nation Enterprises, Inc., purchased a large (36 by 3 feet) gasfired convection oven from Enersyst, Inc., to make its pizza crusts. The oven had problems that the parties were working to resolve, but Nation needed a second oven. It was going to purchase one from someone else, but Enersyst orally promised to fix the first oven if Nation bought the second oven from it. (Oven 1 was beyond its 60day warranty.) Nation bought the second oven, but Enersyst did not fix the first one. Nation sued, but Enersyst claims its promise on the first oven is inadmissible under the parol.evidence rule. Is this correct? [Nation Enterprises, Inc. v.Enersyst, Inc., 749 F. Supp. 1506 (N.D. Ill. 1990)]