The 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 Series 60 heavy duty diesel engines. Significant differences in pumpability characteristics were observed among the test engines, but there was no evidence of pumpability problems in the oils evaluated. In fact, significant pressurization of the oil delivery system occurred during the engine cranking phase, prior to ignition. A comparison of different SAE “W” viscosity grades indicated pumpability characteristics consistent with the J-300 classification system. Good correlations were observed between the MRV viscosity of the test oils and pumpability characteristics in the test engines, both on an individual, and on an average engine basis.