this is new for me
what is a rust converter?
i normally spray wd40 underside to leave an oily surface for water to not to be able to make long duration contact with metal. also exterme cold stiffen mechanical parts, so its good to spray wd40 on calipers etc. always remove extra spray from rotors by test braking car
also driving car frequently prevents rust build up especially on mechanicalparts and air passing through underside of car pushes away sitting water.
dont wash car at night and leave it sitting there till morning without a drive.
leave polish coat on body for prevention from rain and snow.
ive seen in exterme cold weather you cnt even wipe car with a cloth, because ice sticks on glass andmetal . so better is polish protect before it snowing or raining.