I have a 2006 Dodge Caravan transmission fliud how much is needed?

It calls for Mopar ATF+4 fluid but doesn't say how much I need to do a a fluid change.

I would like to upgrade to a synthhetic but I don't know what brands are are the better choice

 

I just did a change on my wife's 05 and it called for about 4-5qts I believe. Also, ATF+4 is a synthetic fluid.