Integral parts of any automotive fluid system are the seals. Elastomers are used in automotive applications for their resilience and rebound attributes. These elastomeric parts are flexible, impervious to hostile engine environments, including hot-stressed additized motor oils. There are a number of standard tests for tensile quality and elongation of rubber seals and parts. Most standard rubber tests are based on quasi-real world conditions. Thermal analysis can be used to evaluate rubber seals and parts for composition by thermogravimetric analysis (TGA). Dynamic mechanical analysis (DMA), thermomechanical analysis (TMA) and differential scanning calorimetry (DSC) can ascertain mechanical strength and the glass transition temperature. T-g. TGA/differential thermal (DTA), DSC and pressure DSC can evaluate the oxidative stability of seals. Results of a TMA and TGA quality control test differentiated pass and fail elastomeric seals and parts. Characterization of several failed seals revealed the sourer of some unique field problems.