Our products are categorized by the oil capacity of the device you are treating. If your engine holds 4 qts/liters of oil, you need a G4 treatment. If it holds 5, you need the next highest number – G6. An automatic transmission with 6 qts/liters of ATF needs a T6A, and so on. If you are unsure of the fluid capacities of your particular vehicle, they can usually be found in your owner’s manual, the link provided on our web page, or you can simply contact us and we will find it out for you!