[btimbit]

Especially on those Canadian tire batteries. They corrode terminals like crazy. Not a real issue if you make sure to clean it often.

Terminal Corrosion and oxidization often looks ashy. The smoke was likely from something spilled, a rag wouldn't just catch fire from being on a battery.

Did it run and drive fine after you got it starting? Start okay after that? Or does it still have trouble?

Oh and don't get the engine flush. That's useless. Modern oil has so many detergents in them to keep your engine clean, you don't need to do anything else. Just a money grab. Especially the friction shield. That's what oil is for