When I purchased my 2017 back in March 2017 I had Expell Ultimate PPF put on. Found bird crap on the hood last week and washed it off but it left a stain and roughness in the film. No way could I get rid of it by normal detailing methods. Was about to take it to the folks that installed the film and remembered that it was supposed to be self healing with the application of very warm water or let it sit in sun. I used my heat gun very carefully and I was very surprised that it came out! This stain was about 3" diameter. Very happy with the results.