The study of material properties is fundamental to the design, analysis, and service life estimation of rubber products. To investigate the usefulness of material test data the paper compares material test properties with those of a moulded product. The material properties include the stress-strain relationship, ageing properties in air and oil and abrasion properties. The study revealed the crucial material properties that directly affect the performance of a valve stem seal (VSS). In addition, a modified least square method is introduced to the Mooney-Rivlin fitting procedure.