Get some hydraulic oil from like tractor supply and run it instead of ATF or PS fluid.. works way better. it takes ALLOOOOTTT more for cavitation to happen.  But no there is no separate lube in the gear box, What you pour in your rezzi goes into it and lubes it.

http://www.tractorsupply.com/vehicle-maintenance-accessories/vehicle-lubricants-oil/hydraulic-fluids/traveller-reg-universal-tractor-trans-hydraulic-fluid-2-gal--0806383  is what i run in my system but you dont have to run that spesific brand