
O-rings are made to be elastic as they are usually stretched to fit into a groove before being compressed. You need to be careful of how you stretch the o-ring while installing it. In fact, you should stretch it more than 50%, and the stretching should be on all the sides, rather than one side.
Pour-point depressants: This additive has nothing to do the actual pouring of your oil. In fact, pour-point depressants help prevent the wax particles in the oil from hardening in cold conditions. As a result, the motor oil flows freely even in low, cold temperatures and the engine doesn’t need to work any harder to pump it.
ERIKS type R (type A according to the DIN standard) is identical in shape to type M, but has a rubber outer case with metal reinforcement on the inside. The rubber creates a good seal in the housing, even if the housing has suffered minor damage or is not in its best condition for other reasons. The RST version has a dust lip. These types are often chosen to replace a type with a metal outer case because they are easier to install and can cope with minor damage to the groove, such as scratches.