Does anyone know why this happens?   There is a 2000 Jeep Wrangler that has had to put in four starters in the past two years?  Its not a hardcore mudder, but it get dirty.   It does it only in the winter months in Illinois.  Every other time its fine.  They say that the bearings start it but i don't know how.  When we contacted Jeep, they said to get the extended warranty and that was it.  We NEED help! Its a daily driver and we are frustrated by how no one can figure it out.  Its only a four cylinder and its pissing me off! Any help is appreciated of any kind.

blow it up : )  

Hmm, that is a lot of starters to go through in 20 years, much less 2 years.  Something is definately WRONG!  What is going wrong with them? How is your battery and cables? Corrosion inside the wire can cause problems.  Do they just quit? Do they click or grind? Are the teeth breaking off? Is the solenoid bad? Did the original starter have any shims on it? Maybe the starter is not aligned with the flywheel properly.  A little mud and road salt/grime should not kill a starter, they are usually pretty tough.

"It does it only in the winter months in Illinois.  Every other time its fine.  They say that the bearings start it but i don't know how." 

What bearings are you talking about? 

I hope you aren't buying a new starter every time.  Buy a starter with lifetime warranty at your favorite local parts store and get good at replacing it.  Many of the rebuilt starters have a better warranty than a new one...

Of course that's not the preferred method....

Is there a heat shield in place?  I went thru the same problem with a GM and it turned out to be a missing heat deflector that protected the solenoid.