I didn't see the Pennzoil stickers, but Amazon has several options. Including one source where you can put your own name on them. How cool would that be.
https://www.amazon.com/s/ref=nb_sb_ss_c_1_15?url=search-alias%3Daps&field-keywords=oil+change+window+stickers&sprefix=oil+change+wind%2Caps%2C170&crid=3OW9PS4UEI3O3