The operating temperature of the primary lip of a radial lip seal is a critical parameter of seal performance. The vehicular industry is requesting unitized seals with extended life for high speed applications. The rubber lined steel running surface configuration used in most unitized seal designs creates an unfavorable operating condition for the primary lip operating temperature. This condition, as observed in testing, is a result of poor heat transfer capability away from the primary lip. An analysis using finite element modeling and a verification technique utilizing an infrared energy measurement device of this heat transfer and of a primary seal lip running on a solid steel shaft is discussed.