Shell Oil Products and MasterCard have teamed on a sweepstakes promotion that will award Chrysler Crossfires to 35 winners, Shell said. A national effort will use print, Internet, direct-mail and radio ads. Print, with lines like, “Use this,” shows a Shell MasterCard. Havas’ Euro RSCG, New York, did creative; WPP’s J. Walter Thompson, N.Y., did media, a Shell rep said. Spending was undisclosed.