When I have the oil changed on my WRX, is it important to use synthetic? Could someone please explain the pros and cons of using synthetic v. standard? Thanks!

Is your car under loads of stress all the time (racing, etc.)? If so, switch to synthetic. If not, dino (regular oil) is fine. Dino is FAR less expensive, and nobody has ever been able to prove to me that synthetic is better except in very high stress conditions. Now, that being said, my WRX is often in very high stress conditions, and thus I use synthetic. I use cheap synthetic (Valvoline), and have had no problems yet.

Once you switch to synthetic, don't switch back because it can cause damage to your engine.

Is your car under loads of stress all the time (racing, etc.)? If so, switch to synthetic. If not, dino (regular oil) is fine. Dino is FAR less expensive, and nobody has ever been able to prove to me that synthetic is better except in very high stress conditions. Now, that being said, my WRX is often in very high stress conditions, and thus I use synthetic. I use cheap synthetic (Valvoline), and have had no problems yet.

Once you switch to synthetic, don't switch back because it can cause damage to your engine.

I dont race or anything, I do however, drive in the mountains a lot (live in CO). I used synthetic last time I had the oil changed, will it kill me to switch back? Is mountain driving high stress?

"Mountain driving" is not necessarily high stress. You should be fine with regular oil. Use a blend in between the synthetic and the dino, though. I'm pretty sure you don't have much buildup in your engine yet, but better safe than sorry.