I went to clean and spot spray my car with permatex heavy duty but much of my coating simply flaked off in the wheel wells that I decided to go ahead and redo all of it.
Wanted to get some opinions from guys who have redone there wheelwell/under car coatings to see what brand or application style held up the best. Don't exactly want to have to do this again in 2 years.

 

3M undercoating is great and all I've ever used in the body shop and my personal cars. Be sure to rinse the area's you plan to undercoat with a pressure washer and let dry. This will help adhesion and longevity, nothing will last long if applied on top of dirt and grime.