Gear oil question

[Scottcoda]

I noticed an old wet stain on my Dana when I first bought my truck. I never really had a chance to look at till recently. It looks as the gear oil has now turned to gear grease.. Awful greasy mess in the pumpkin.. I am looking for any advice as to clean it up before replacing the seal and adding fresh oil.. A friend suggested I put some kerosene in the pumpkin and drive a few miles to loosen the old oil up.. It makes sense to me but sounds a freaky.. Has anyone done this or have any other advice.. Thanks guys