I also have a set of Campy Neutron wheels.
Campy recommends lubing the hubs every 1,200 to 1,800 miles.
You need a grease gun with a needle nozzle. These can be found at the local hardware store, Home Depot...etc.
Here's a web site with a pic of what you need. It's the same one I use. Works perfect.
http://store.autotoolexpress.com/ast101.html
Usually about every 1,500 miles I'll give the hubs a few pumps of grease. If you "over" grease the hubs, grease will typically ooze out of the ends of the axle shafts. This will show up after a ride, due to centrifical force of the spinning wheels. Not a big deal, just wipe the excess off. So, for the next few rides after you lube the hubs, check for any of that excess grease.
Grease ? Any good bearing hub cycling grease will do the trick. The fellas at my local shop use "Finish Line". Lots of good ones out there.
Good Luck !
