For those of us living in the road salt belt I have a suggestion for you. I already did mine before the winter and will do it again this spring. The way the rear differential case is cast provides pockets for salt from road grime to accumulate. Salt and aluminium don't mix. After my friend told me how many Encore and Trax rear differential he changed because these pockets would corrode right through the case which he says is only about 3/16 of an inch thick if that. Manufacturers do it this way to save on weight and casting material. He suggested cleaning these pockets and filling it with the thicker rustcheck or similar rust protectant. I used that dripless undercoat that almost looks like vaseline once applied. Here is a picture of a differential off of the vehicle, you will see why... Maybe 10-15 minutes may save you a ton of money and hardship. It is a really bad design for our wintry salted roads.