I purchased a used class B with an Onan generator. One of the sales points was the genny had only a few hours on it. After learning about maintenance of generators, you need to run the genny for 2 hours each month under load to keep it working, running smooth. Therefore I found the genny was in dire need of an overhaul. Luckily basic maintenace plus one minor choke part was all that was needed. Now I put at least 2 hours a month on the unit and keep monitoring the oil level when I do this. My best advice is to read the required maintenace in the genny booklet and follow it. You never know when you are going to need to fire that genny up and save your trip. Good luck with whatever unit you decide on. Now that our Onan is working, love it.