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1. I am very anal about undercarriage cleaning (ya know what I mean) both summer and winter, even though I offroad the car. The red clay here rusts things out just as bad as salt, and in the winter, we get salt too. I also have a 1200ft long red gravel driveway to add to the undercarriage mess. Normally I just go to the coin-op carwash, and use the power rinse to hose off the underside, then I go home and wash the topside myself (in the summer). In the winter, I just keep the car hosed off as much as I can. I did do a full detail the other day though, it got up to 50F! lol
Every spring all of our vehicles go up on jack stands and get pressure washed underneath. Mechanics are always amazed.
2. Not entirely, but I'm not OCD about it. I put a good coat of insulating wax on it in the fall, and keep the grime buildup off it by hosing it off (as mentioned previously).
3. I don't use anything, as the RainX just comes right off (seems to in the summer now, too?

I wonder if they changed the formula). My wipers work better on the plain windshield surface when it comes to removing road/wintery grime without streaking.
We have mild winters down south for the most part, but I'm also used to dealing with MN/ME winters as well. :biggrin: