Lubricating grease typically has natural sealing properties. The solid thickener component of grease can form a barrier at the edge of a seal that helps to limit or prevent leakage of fluid through the seal. Many seals are designed to be used with grease for this reason. Elastomers can be formulated to slightly swell and soften when in contact with lubricants for use in seals. This behavior generally improves their sealing capability.