Thank you for your interest in Berryman! We have multiple gasoline fuel additives, including the two you mentioned, that will provide cleaning in different parts of the fuel system. Depending on the application, the usage frequency will vary. Berryman B-12 CHEMTOOL FUEL SYSTEM CLEANER (part #0116) is an excellent preventive maintenance product for fuel injectors, carburetors, and intake valves. It should be used every third fill up. Berryman B-12 CHEMTOOL FUEL INJECTOR CLEANER (part #1112) will clean up dirty fuel injectors, and one bottle treats up 12-20 gallons of gas. It should be used every third or fourth fill up. (If you’re using 0116 regularly, then you could simply replace an #0116 usage with #1112 occasionally.) Berryman B-12 CHEMTOOL CONCENTRATED INTAKE VALVE & INJECTOR CLEANER (part #3012) is a bit stronger than #1112 and will clean up dirty fuel injectors and intake valves, and one bottle treats up 12-20 gallons of gasoline. It should be used once every 3,000 miles. Berryman B-12 CHEMTOOL TOTAL FUEL SYSTEM CLEAN-UP (part #2616) is our strongest detergent-based gasoline additive and will thoroughly clean dirty fuel injectors, intake valves, and combustion chambers, and one bottle treats 16-21 gallons of gas. It also eliminates “octane creep,” a scenario where carbon buildup in the combustion chamber causes the engine to knock/ping at octane levels it previously ran well with. 2616 should be used every 5,000-10,000 miles. If you want to know that you’re starting with a clean fuel system—especially on a high-mileage vehicle like your Grand Cherokee—then we would recommend starting off with a can of 2616 at 1 oz/gal. After that, start using the 0116 every third tank for great keep-clean performance. For maximum cleanliness, either use 2616 or alternate using 3012 and 2616 about once a season. Coupled with a proper tune-up, that will maximize your fuel economy, catalytic converter and fuel injector life, and overall drivability.