I usually start mine ip once a month and let it run for a bit
That's not really a good idea.
They never really get everything up to operating temperature and end up condensing moisture inside the engine which combines with combustion gases and produces an acidic waste that just lays in the engine for long time periods causing internal corrosion damage.
I just take mine out on a nice day for a little ride , maybe once or twice a month ,but the winter's in N.J. arent usually that bad ..........
and yes i heard just letting it idle for a while is not good ,you need to drive it
I wanted to switch to synthetic oil but since I have never used it before I'm afraid of switching to it now
I have read that if you wait to long (no idea what too long is) to switch that the synthetics will remove the gunk around your seals and this can lead to them leaking. However I have no personal experience with that.