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The cold starting and low temperature pumpability performance of twenty-one new and used multigrade oil formulations was determined in fired engine tests conducted with Caterpillar 3406B, Cummins NTC-365 and Detroit Diesel S-60 heavy duty engines. Viscosity grades included SAE 0W-30, 5W-40, 10W-30, 10W-40 and 15W-40, formulated with various commercial viscosity index improvers (VII's) including olefin copolymer (OCP), dispersant multifunctional olefin copolymer (MFOCP), polymethacrylate (PMA) and styrene-isoprene copolymer (SICP). Significant differences in pumpability characteristics were observed among the test engines, but there was no evidence of pumpability problems with the oils evaluated. In fact, significant pressurization of the oil delivery system occurred during engine cranking, prior to ignition. Good correlations were observed between the MRV test oil viscosities and pumpability characteristics in the test engines, both on an individual and on an average engine basis.