I searched everywhere about this issue, and it seemed to be unusual thing to happen.. I have 3 chargers(including the USB cable). One that came with my current Thunderbolt, one from the LG Ally I used to have, And one from the featured phone I used to have years ago. I use both of them now. This issue actually happened when I had the Ally. From some point when I take out the phone from the charger, either on the mini usb port on the phone and the metal part of the charger jack is covered with some green greasy oil on it. And with the green oil filled in mini usb port on the phone, the oil is now transferred to other chargers I have and now even the port of relatively brand new Thunderbolt is filled with that green thing.. At first I didn't notice it as a big deal, but it's been quite a while and I'm worried now.. WHY AM I GETTING THAT GREEN GREASY OIL ???????????????????? AND WHAT IS THIS GREEN THING?????????? I think the first time I saw this green oil thing was from the charger I got from the featured phone. Would the reason be that it's too old? I'm also wondering.. Ive been hearing squeaking noise from the adapter of this wall charger whenever I plug in my phone to it. Why is this happening? Do I just need a new charger? If can, how can I clean up the green mess in my TB's mini usb port???