A test was developed by the Cummins Engine Company to evaluate Diesel fuel quality and potential additive effects. This test utilizes a Cummins L10 Diesel engine with a PT fuel system and stepped plunger injectors. A modified CRC rating system is used to quantify deposit levels.This paper further investigates the L10 Injector Depositing Test and will focus on Diesel fuel and additive variables. In the original work, the bulk of the data was collected on an industry standard reference fuel, Cat 1-H, as opposed to commercially available Diesel fuels.Commercially available Diesel fuel varies in composition with regard to sulfur level, percent aromatics, final distillation end point, and cetane number. To evaluate these fuel properties and their possible effects on injector deposit formation, two test matrices were designed. The first experiment is a 12-run fractional factorial design with four factors: additive level, sulfur, aromatics, and 90 percent distillation point (T90). Several Diesel fuels were blended to achieve specific levels of the three fuel properties; these represent a range of fuel properties that can be found commercially. The second experiment, a six-run factorial design, evaluates the effects of cetane improver and additive level on deposit formation in a commercially available fuel. The first design was run at Engineering Test Services, while the second was completed at AutoResearch Laboratories; both used the procedure described in SAE Technical Paper #912331.The paper presents conclusions on various fuel compositional effects as seen in the L10 Injector Deposit Test. Additionally, the effects of the various additives and additive concentration are discussed. The use of designed experiments allows a discussion of the statistical significance of the effects of fuel properties on deposit formation in this test. This data, combined with Lubrizol's large L10 data base, will facilitate future test refinements and eventually help to evaluate the suitability of this test for future Diesel fuels.