The effects of oil derived poisons and thermal degradation on three-way automotive catalysts is investigated. Dynamometer rapid aging test (RATsm) schedules that incorporate both thermal and oil-derived poison degradation are used to age catalysts for FTP emissions studies. This paper presents three investigations. Vehicle aged converters are analyzed to determine the axial phosphorus distribution through out the catalyst. These phosphorus profiles are compared to dynamometer RATsm aged catalyst. Also, 27 converters were RATsm aged on three different RAT schedules at three different accelerated poison levels. The amount of phosphorus on the catalyst is compared to the amount of equivalent oil consumed by the aging engine. Finally, 24 converters were aged on three different RATsm schedules to determine the effects of catalyst volume, aging temperature and oil derived poisoning on FTP emissions using both Pd and Pt/Rh catalyst technologies. Results show that the RATsm schedules with poisons can apply a poison distribution that is similar to vehicle aged catalysts. The effects of the oil derived poisons can be easily seen with small catalyst volumes. Accelerated catalyst aging schedules should include both thermal and poisoning degradation.