A new radiotracer technique for determining wear rates of selected automotive engine parts is described and demonstrated for piston rings. The technique uses Fe55 instead of Fe59 as the radiotracer. A liquid scintillation method for counting Fe55 is necessary since it decays by electron capture and emits only the Mn characteristic X-ray of 5.9 keV. A simple method for extracting the wear particles from the engine oil and getting the iron into the liquid scintillation mixture is described. Counting yields of 8 to 9% are obtained by the method. The Fe55 technique of wear measurement does not directly compete with the existing Fe59 technique since slightly lower sensitivity and longer sample preparation is required. However, the much longer half-life (2.6 years as compared to 45 days) and the lower radiation energy (5.9 keV as compared to over 1 MeV) allows the Fe55 technique to be used for long-term wear studies, for double tracer studies, and for studies of large engine parts.