Don't change your oil every 3,000 miles. Take a look at your owner's manual, most manufacturers recommend changing your oil every 7,500 miles depending on driving conditions. Some cars can go 10,000 miles or more without an oil change.
If it's yellow, let it mellow. If it's brown, flush it down. OK, this one is pretty much self explanatory. If it starts to smell, flush it. A single toilet flush is anywhere from 1.6 to 5 gallons of water, and most of us flush the toilet at least 5 times a day.