Seems unlikely that one bad tank of gas would cause that much damage. Sounds more like a coincidence to me.
I know a guy who owns 5 gas stations and an oil distributorship. He says there is a difference between oils, because of additives, but that all of the gas pretty much comes out of the same big storage tank. His stations represent two different oil companies, he hauls his own gas (has two tanker trucks) and I'd be willing to bet it all comes out of the same tank.