synthetic or regular oil?

i bought my car w/ 48000 miles, and now i have almost 68000. i've never put synthetic oil in my car. i've always used reg oil. anyway, i've heard that synthetic oil is bad for the car from a couple of mechanic friends of mine. is this right? is it worth it to change to synthetic now (if it is indeed better), or should i stick w/ reg oil?
btw, i usually drive my car nice in the city and hard on highways which is about 4-5 times a week.

Synthetic oil is not bad for your car. I would probably stay away from those mechanics. But, if you change your oil every 3000 miles, you probably don't need it. I'm kinda anal though, i use synthetic and still change it every 3000 miles.