I am not sure what weight grease these things take, but I always use Mobil 1 Full Synthetic Grease for all automotive and bike lubrication.
I have used the Mobile 1 for the following.
1) Rear Derailleur Free wheels
2) Headset to Steer rod contacts
3) Pedal bearings
4) Front thru axle and the QR skewers
5) All fastener treads that need greasing.
6) Front Specialized Hub on my FSRxc w/ball bearings.
Mobil 1 is a tad heavier than say Moly and Li grease. It lasts for over 6 months even under constant usage. Even with the viscosity being high, it still allows ample movement for all moving parts. I dont see any issues using Mobil 1 for a Front or rear Hub
ZTR uses sealed bearing and is maintenance free, if anything, grease the pawls and the spring after cleaning them thoroughly. Use very light grease like the Chris King (small container is about 10 bucks in ebay), why do you think you need to grease your hub? the freehub might go before the hub so you might want to look into replacing that if youre starting to notice issues with performance like binding when youre coasting or slipping when under load. Hope that helps.