The Effect of a Gasoline Additive, Automobile Make, and Driving Cycle on Intake Valve Deposits (IVD) and Combustion Chamber Deposits (CCD) in a Ten Car Fleet Test

In a ten car fleet test, the amount and chemical composition of intake valve deposits (IVD) and combustion chamber deposits (CCD) were determined. Five car makes, three driving cycles, and a gasoline with and without an IVD reducing additive were used.

The amount of IVD and CCD were a strong function of car make, and the additive decreased IVD and increased CCD compared with non-additized base gasoline. The chemical changes in the composition of the CCD show that the additive was the source of the increased CCD.

For all vehicles tested, a modified AMA Driving Cycle and a BMW Driving Cycle produced similar amounts of IVD and CCD, with similar chemical compositions. In contrast, the high speed cycle produced less CCD and gave CCD and IVD that had a different chemical composition than that of the other two driving cycles.

No CCDI (combustion chamber deposit interference) and no driveability problems occurred during the normal course of accumulating mileage.