If you look for a local source for the Methanol, you will find it is pretty expensive per drum due to the purity. Also, I have the feeling transporting a drum of flammable liquid violates the local DOT codes. A commercial manufacturer of Washer Fluid buys lower quality methanol in bulk. They add the soap or ammonia because some people actually us this liquid to clean their windshields. Watch for a sale and you can find gallon jugs fairly cheap. I purchased 110 one gallon jugs from Menards. The cashier never asked why. Beat Juice is the best product due to the weight of 11 pounds per gallon compared to washer fluid just over 8 pounds per gallon. However, since Rim Guard is a service, you will pay a lot per tire. Also, if you spring a leak, you lose your investment. I have done two tractors with washer fluid and I am happy with the results. As for corrosion, as other have pointed out, you need oxygen and places where the corrosion cell can concentrate salts. If the rims are clean and painted, they will be fine with washer fluid. If they are rusty to start, the rust will continue.