I changed mine at about 23,000 miles and it didn't really need it. The chain was OK and the rear sprocket showed no visible wear. The front showed just a slight bit of wear. I changed just for peace of mind. I lubed my chain about 4 times total in 23,000 miles and never cleaned it.

I learned all I need to know about life by killing smart people and eating their brains.
Eat right ,Exercise ,Stay fit, Die Anyway!