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The present work investigates the impact of lubricating oil formulations on efficiency and durability of Diesel particulate filters (DPF) by means of tests on a passenger car diesel engine retrofitted with a continuously regenerating DPF. An accelerated test procedure, characterized by oil injection into the intake air manifold to simulate a higher oil consumption, was designed and used to enhance the oil effect on trap weight increase and exhaust gas backpressure. Different prototype oils, designed to evaluate the influence of key additives characterized by a different elemental content, were used. The accelerated tests revealed to be a good tool to discriminate, in a short time, oils having a different impact on DPF performances. The main role of oil consumption and oil ash content emerged from the tests.

A test procedure was set up in our laboratories to evaluate the propensity of fuels and lubricating oils towards the soot accumulation in Diesel Particulate Filters. The experimental work was carried out with the use of a passenger car diesel engine, retrofitted with an aftertreatment system composed by an oxidation catalyst and a DPF. The soot propensity was evaluated by means of repeated measurements of differential exhaust backpressure gradient, during a running period at mid load and speed. The specific fuel consumption gradient was also measured to find a correlation between both the variables. After each soot loading period, a burning off period at full load was operated for the purpose of filter regeneration. A two-phase experiment was undertaken to assess repeatability and discrimination capability of the test procedure. During the first experimental phase, repeated tests were conducted on a fuel matrix containing some surrogate fuels.