:In the past ten years, there has been a radical change in automotive engine and transmission sealing technology. For example, molded rubber gaskets have supplanted the traditional formed-in-place gaskets and cork rubber compositions as the preferred sealing mechanism. The vast majority of these new gasket designs are currently manufactured from silicone rubber (VMQ). Although VMQ has demonstrated an outstanding performance record since its introduction to these new applications, it does have several deficiencies which limit its use. For this reason, formulations based on alternative organic polymers have been developed and are available for use in applications where performance improvements are desirable. It is the intention of this paper to focus on optional elastomeric formulations which are now available to satisfy increasing warranty demands of the automotive power train. Long term aging studies in engine oil and automatic transmission fluid will be used to demonstrate the merits of VMQ, ethylene acrylic (AEM), ethylene vinyl acetate (EAM) and polyacrylate (ACM) formulations as candidates for these applications.