The washer fluid contains alcohol that is the same as rubbing alcohol.  A guy dropped his bullet mold in rubbing alcohol to try to preserve it and it rusted in the jar.  Denatured alcohol contains no moisture and can be picked up at the hardware store.  I still use the old hot water and soap method and it is messy - but it works for me.  I think it is like bullet lubes where everyone has a formula or product they use with success.  It just keeps everyone interested in looking for their silver bullet and keeps everyone busy experimenting.  It's a fascinating facet of this sport.

Oil mixed in alcohol will no doubt inhibit any corrosion.  I looked up isopropyl alcohol just for kicks and it appears every maker has different additives.  It does say it contains water and I'm sure the molds left in the solution contained nothing but the alcohol.  They were in the jar for a few weeks and came out with large blotches of rust and some pitting.  I don't know if it was the alcohol or something on the mold that caused it - but I avoided using it after his misfortune.   I know that using rubbing alcohol for cleaning steel before bluing will leave a mottled finish and it may be due to those additives.  I baste my molds with lard that kinda cures them like a skillet, and it seems to work well for me.  It's interesting to see what everyone comes up with and uses.  Another quirky thing is that I discovered that using just my well water instead of distilled in my bluing tanks seems to give the finish of steel a brighter sheen.  I have not  a clue why this happens, but I did it that way for 30 years.  Of course I mixed my own blue solution and that may be part of it as well.  It's just one of those things that makes you go... Hmmm?