Methods are provided for forming an asphalt fraction corresponding to a blend of asphalts, the asphalt fraction having at least one property that is unexpectedly better than the expected property value based on the individual asphalts used in the blend. The unexpectedly beneficial blends of asphalts are formed in part by including an effective amount of a Napo crude oil or crude fraction in the feed used to form the asphalt fraction. For some asphalt blends, including an effective amount of a Napo crude in the feed can allow for production of an asphalt with a low temperature performance grade that is lower than the predicted value by at least 0.5° C., such as at least 0.75° C. or at least 1.0° C.