Rung trusts him. Well that's more than he can say, he doesn't quite trust the Autobot, not yet. Although why would Rung let him basically eat him if he couldn't be trusted? It wouldn't make sense.

"Oh... Just hooking up fuel lines and stuff like that." is Rung finally changing his mind? Not that he'd blame him.

"It takes a lot longer," he explains, while trying to find a good place to put his hands. "Direct access I can drain a core in about a breem. Going the hook up route takes me a whole night to drain a core... Sometimes a bit longer."

Why it's like that who knows, blame the bayverse Dead End science probably, but he's no scientist.