This may sound like a dumb question but I just got a new bike. After my first week of riding and putting on about 100 miles i oiled the chain today for the first time. After I oil it is the chain supposed to produce that black grease? I know the chain is supposed to stay clean and what not but it seams like after I oiled the chain its producing a high content of the black greasy oil. Is it supposed to be like this or not?