Checkout automotive fuel line deicers if you want an 99% alcohol. Its relatively cheap and its available in methanol, isopropyl and occasionally isobutanol in aviation applications.

Ballistol contains a little isobutyl IIRC, adding a little more ISO to it for swabbing after flushing with hot water should help reduce flash rust. The extra alcohol should mix with the water and help it evaporate more quickly and then leave the mineral oil behind.