ive been using zep apc at 10:1 as my go too. locally its cheap for the gallon. ive seen multi x ,d101 , and now Gyeon came out with an apc. are they pretty much all the same? would there be a better alternative to what I have now? looking for something safe for all interior and exterior including aluminum. ive never used zip at 4:1 either, it seems to work fine at 10:1. I don't get my cars that dirty to use heavy dilution. but with winter it comes in handy if a product works faster than another!