The mixing of Kerosene or #1 diesel will not clean up the system. Only a fuel treatment will clean up the system. The use of #1 diesel, or mixing in Kerosene, is for cold temperatures to increase fuel flow and to reduce clouding. Page 8.15 of the Owner's Manual gives the proper mixture formulas for a given temperature.

One of the best products for cleaning out the tank and cleaning the injectors, and keeping them clean, is Howes Meaner Power Kleaner. Howes Diesel Fuel Treatment is best for removing water, but Meaner Power Kleaner also works well. Power Kleaner should be used in every tank. 8 ounces per tank if you're only using the Power Kleaner, or 4 ounces if you are mixing it with 3 or 4 ounces of something like Power Service. Power Service is also very good for dispersing water and for a cetane boost, which for a Sprinter (or any turbo diesel) should be used to get the cetane upwards of 50 cetane. The increased cetane that Power Service gives you will reduce carbon buildup in the combustion chambers and allow the Power Kleaner to better perform its job.

Be thankful that you don't have biodiesel in your area. While biodiesel will increase the cetane and lubricity, the tradeoff is bioresidue that tends to clog the injectors unless a good fuel injector cleaner like Meaner Power Kleaner is used in every tank. Mercedes recommends a maximum of 5% (B5) biodiesel, anyway, but most commercially available biodiesel is B10-B20. If you regularly use B10, then a fuel injector cleaner is a must in every tank.