I like to run metal shields except on the tires and throw a few drops of Bocas Lighting Lube in the bearing before qualifiers and definitely before any main. I have seen the bearing life increase significantly just by cleaning them after a day of racing and adding a few drops of the Lighting Lube too. I really believe Bocas ROAD GREASE POWER extends the life of your diff cups and helps provide an excellent seal to keep the diff oil where it should be, in the cup, not on the chassis. All in all I have never been disappointed with Bocas products and have no plans to use any other manufacturer products. If it works don't try and fix it and Boca works.