If you want to do the work yourselves or if its not under warranty, we sell the Pure Prep and the Kryptonite Metal Treatment as a bundle package on our website or on Amazon.
Authorized Dealer
EnviroGreenSolutions.com
You should be using Kryptonite Metal Treatment which is what GMC suggest you use for any corrosion, we are the only authorized product for it, we currently sell a bundle package with has the PurePrep + 3 cans Kryptonite you can purchase it on our website or on amazon.com
Best of luck!
EnvirogreenSolutions.com