The drain plug for the transmission pan is stuck, I broke a bit trying to get it loose. I removed the pan and tried a little heat and Vice Grips on it and it wont budge. Not wanting to buy a new pan if the threads are messed up, I am not going to drill it out. Is there something I can put on the outside of the drain plug to make sure it doesn't leak in the future? Or will I be better off just leaving as is as it wasn't leaking and didn't budge?