I was lucky to have close to me a locally owned tire and auto shop with great mechanics and twelve bays, one of which they built especially for RVs. Two generations of family ownership and the father and son were both very active in the community and first class guys. Well, the ownership didn't make it the third generation and a couple of years ago they sold to an out of state outfit that, of course, changed a lot of things including no longer working on rvs, even a camper van like our Roadtrek. They worked on two Bs and two Cs for us over the years.
My "fall back" was a locally owned quick lube and service that was, again, family owned and two generations. It is small with three bays and one is for doing mechanical work. The guy that is a manager and owner has thirty years experience being a mechanic and is a first class guy. He is happy to work on the Roadtrek and has great knowledge of older vehicles, which is not easy to find. I have known him for a long time.
They fully inspected my RT and put in new plugs and wires and said I didn't really need anything else and they did it for $500 including oil change. That was about two years ago.
So, I have been really fortunate.