you should go to napa. seriously they are the best place to get grease, lubes, oils, everything right down to a socket conversion... and if you know some people that work there, they can get you a huge discount. i picked up five quarts of oil, three bottles of gear lube, an oil pan, injector cleaner, and an oil filter for under 50 bucks. napa is the place to go. the usually know what is going on with your car/truck better than any autozcrap employee ever does. you know what i mean.

 

Two questions, how does the plug look (is it really stiff and dry rotted), and when was the last time the gear lube was changed (the more important of the two questions)? I've never seen a plug wear out, and since the fluid level is below the plug it really shouldn't stream out. My guess is, it's time for a fluid change, because it seems that the fluid has lost it's viscosity and when heated up it expands more than normal, and that expantion is enough to force it out the plug.