You're taking a risk using expired films, "problems" such as color shifts (slide films) and loss of contrast (black & white films) usually occur. Unless your subject matter doesn't justify buying a fresh roll of film, or you're cross-processing (then expired films become the choice film), I'd ditch the old film.
4 years in cold storage is a long time for a roll of film (or anything in the fridge), you'll probably get unsatisfactory results from it.
mmm.......try to push the film 2 stops and u may get some yellowish effect(for kodak's EPL Cross-process)rate it at ASA 800.....use the film after 1 hour after u take out from the frigde......... ..........there may be different effects according the exp. date........results may defer from time to time.