I just had my differentials serviced. Noticed oil on the driveway under the front diff. It's clearly leaking from the fill plug in front. I had it parked pointing slightly downhill. I was thinking maybe a slight overfill and the downhill combined to bring the level too high. I have turned the truck around and parked it pointing uphill to see if that stops the leaking.

But, it seems to me that oil shouldn't be weeping through the threads of the plug like this. Is there something the mechanic should have done with those threads to seal them? It doesn't appear to be cross threaded.

 

Check to see if it will tighten up some. I use Teflon tape on mine. I use the stuff for gas line it is thicker than the normal stuff.

 

I called the mechanic and he said to bring it in. He thought maybe a gasket may have been crushed while torquing it down. He replaced plug and all. No leak now.