It is important that any seal in contact with a lubricant is compatible with that lubricant. The base oil in a grease may soften, harden, shrink, or swell elastomers used to make seals. It is advisable to check the compatibility of the lubricant with the seal material before putting a grease in service. Many grease manufacturers and seal suppliers have data for compatibility of standard elastomers with common greases, oils, and other fluids. In some cases, it is preferred to run compatibility tests between the grease and the seal or seal material at the operating conditions.