Stock Toyota inner axle seals are prone to failure from the beginning. They do a horrible job of sealing inbetween the factory inner axles and the axle housing itself. Why does this matter? The birfields are designed to have higher viscosity lubrication (not gear oil) When gear oil seeps past the factory inner axle seals, you have 2 things happen. 1. The Birfields can wear out quicker and 2. The oil seeps out the front axle housing because the wiper seals are meant to keep in the grease, not oil and keep out crud and debris. These axle seals fix the common problem at a great price. They are incredibly worth the investment.
