oil types

My moms 06 elantra. 2.0, has 31k on it (she doesnt drive much). I want to change to synthetic oil. The dealer said he doesn't recommend it. I cant see why not. Car is in top shape, no problems whatsoever. Opinions on why he said that? I want to use it for the cold flow properties and protection. We live in a northern climate and I cant get her to even let the car idle for 1 miute after she starts it.

At those miles I would not hesitate to put Synthetic in it... Don't see what it could really hurt.. Those engines are sealed up quite well, seem about the only common leak was the valve cover gaskets... Seems normal for most all DOHC 4 Cylinders to do that tho...