I understand the safety net of going through a dealer. Honestly it's a false sense of security. It's basically a used car. You buy it, it's yours. When your tail lights disappear around the corner from the dealer's view, you're on your own. A portion of that extra money paid to a dealer for services would be better spent on taking the bus to a truck repair shop. Go basic. Get your fluids and filters changed. Most bus barns have a commercial shop nearby that they use regularly.
The point is you're going to learn just about everything to do with the bus anyway. It seems like a lot to learn, but it's done an inch at a time. You've already learned a lot about buses, diesels and transmissions since you've been here.