At 36,500 miles while driving my TB in A4WD in the snow on the highway the RPM's reved up to the max, engine lost power and I heard a loud grinding/clanking sound. Switched the car back to 2HI and it rode ok. Ever since that day when put into 4WD the front tires lock and the car will not move. Dealer says that the front differential oil that normally has about 2 quarts in it was down to 1 teaspoon. He claims that there is no leak. However the oil was changed at 34,000 and at that time the front differential oil level was checked and it was ok. The dealer says that because of this oil being gone, the ball bearings have melted to the front axle and that is why the car cannot be put into 4WD. Does this make any sense to anybody? I could use any help you have. How does the oil just disappear? What would be a possible reason for that? I have read a lot about this "sun sheild" transmission problem on forums and was fairly certain that that would be the problem. I was not expecting this news. The worst part is that they refuse to pay anything for it because it is not a defect in the vehicle that the oil was out (I am questioning whether it may possibly be some problem with the vehicle). I asked if they was anything that I could have done to prevent the problem (I have always maintained regular maintence/service) and he said no. So I am stuck paying for a new front differential and possible axle. I am wondering if he could be giving me a run around here? Any ideas?