Generator Maintenance Kit; For Use With Cummins 5.8 HGJAD Gas Generator Model Onan generators are known for their high quality and dependable performance. The best way to maintain that performance is by using genuine parts. These parts are designed and engineered specifically for your Onan generator to perform at its peak. The Onan RV Generator maintenance kits are designed as an on the go solution for you while on the road. Get all the necessary materials to perform basic preventative maintenance at your final destination.