Answer:
I am longer than a decade and shorter than a millennium
I cannot be burned in fire or drowned in water
I always murmur but never talk. Always run but never walk. I have a bed but never sleep, have a mouth but never speak. What am I?
There was a girl half my age when I was 12, now I am 66, how old is she?
I can be winding and I can be straight. I can be smooth and I can be rough. Sometimes both. I start out black but fade to brown. My favorite colors are yellow and white and I love stripes and dashed lines.
No matter how little or how much you use me, you change me every month.