AIO is definitely NOT just for new finishes. It will do a great job cleaning up your paint and providing decent protection and gloss. In fact, most consider it one of the better chemical paint cleaners on the market.
That said, paint cleaning is only one step in the process of detailing, and surface prep is critical to obtaining the best results. For paint that has not seen any TLC in years, you will definitely want to clay the surface prior to applying AIO. The clay will remove imbedded contaminants and really smooth things out. You might also want to use an abrasive polish, by machine, to remove any swirls or micromarring.
After claying and polishing out swirls, it will be time for the AIO. While AIO will clean and add some protection, topping it with Klasse SG or another "LSP" (last step protectant) would be recommended. In general, lighter colors seem to do better with sealants like Klasse SG, but I've found that my Robins' Egg Blue T-bird actually looks better with a good carnauba LSP.
Something like Wax as you Dry will work pretty well to maintain your finish in-between major detailings.
That said, paint cleaning is only one step in the process of detailing, and surface prep is critical to obtaining the best results. For paint that has not seen any TLC in years, you will definitely want to clay the surface prior to applying AIO. The clay will remove imbedded contaminants and really smooth things out. You might also want to use an abrasive polish, by machine, to remove any swirls or micromarring.
After claying and polishing out swirls, it will be time for the AIO. While AIO will clean and add some protection, topping it with Klasse SG or another "LSP" (last step protectant) would be recommended. In general, lighter colors seem to do better with sealants like Klasse SG, but I've found that my Robins' Egg Blue T-bird actually looks better with a good carnauba LSP.
Something like Wax as you Dry will work pretty well to maintain your finish in-between major detailings.