Hello, torn axle boots are the beginning of a serious problem. When the boots are torn, not only does needed grease escape the joint, but debris gets in as well. As a result, abnormal wear and damage can occur to the joint if you continue to drive the vehicle. It does not take long for this to happen!
The grease needed will come with a boot or joint kit used to repair the concern.
You may be able to locate a "universal" split boot, but these are miserable and highly discouraged. It just simply doesn't work and doesn't last.
Seek guidance from a local technician who can properly replace your boots, joints, or axle shafts, following a proper evaluation. Often times, you can locate remanufactured axle shafts for the fraction of the price of replacing even boots, as there is much less labor involved to remove and install an axle shaft, rather than disassemble joints, clean, lube and reinstall with a new boot at each point -- especially if both boots on one axle are torn already.
This is not a "do it yourself" job, unless you have pneumatic tools, secure and stable vehicle support lifts and stands, and other proper "clean environment" equipment at your disposal.
