I have a 04 rubicon that I just added to my stable and plan on changing the fluids. I believe i just read a post that said running a synthetic fluid will cause the air line for the locker to swell and leak in the diff, causing it to not work. This is the first I have ever heard of this. Just wondering if this is the case so I don't screw up my new truck. I just seemed a little weird to me since the line is in a petroleum product, that a synthetic would cause a problem. Please help! My Cherokee has air lockers, and I have been running a 75w140 synthetic with no problem for 2 years. Any light shed on the subject would be appreciated. Thanks:scared: