Regular servicing of your differential will increase it's life span and reduce friction. ECS Tuning has created a kit that includes everything you need, including a gasket, drain/fill plugs, axle seals, and Redline 75w90 oil. Redline gear oil is a favorite among M3 enthusiasts because of it's low friction, high wear resistance properties.
Make your differential service count.
See kit contents tab for a complete list of included components