Careful with this product. It works GREAT, but... it'll turn plastic into a brittle POS in about 3 months of continuous use.
I raised my shield and it just crumbled in my hands.
I use regular Honda polish or diluted wax. Nothing works like Rain-X tho.
RAIN? Be smooth. I don't slow down that much but I'll give the vehicle in front a bit more room to compensate for the cager who's tailgating me.
Even if all the sand and oil/grime washes off - after the rain you're dealing with a "green" track, road temps will be down as will your tire temps and traction will suffer a bit because of it.