You have to consider the speed at which the shaft will be moving, the housing bore, and the runout. These are important to make sure that you choose an oil seal that will not be exposed to unconducive abrasions.
The major cause of extrusion and nibbling is stress caused by high pressure. This is commonly noticed when the oil seal has a chipped or nibbled look. In fact, in some cases, the surface of the seal tends to peel on its own, which makes it have a shaved look. What the stress does is that it increases the clearance gap between the mating edges, which causes the seal to get entrapped, and then leads to severe physical damage.