Yes, that is absolutely normal in a gas engine. In fact, if it is brown when you first change it, then the engine is relatively clean and the oil changes are being kept up with.

The black that you are seeing is soot. If you will use one of the Universal grade oils that is designed for over the road diesel trucks, there are additives to help deal with the soot. These are oils such as; Chevron Delo 400, Shell Rotella T and Mobil Delvac.

Good luck,