naturally you'll have to clean all the fluid film off, powerwash, wirebrush, prime with denatured alcohol etc. Eastwood sells a prep that goes along with all there rustproofing products. or you could use denatured alcohol or gas.
Chances are, it will be washed off by spring...we did my dad's truck with fluid film and it was completely washed off and dry by spring. This was a SINGLE Pennsylvania winter and about 150 miles a day.
We went back to our mix of oil/ATF.