A test program has been conducted to evaluate the low-temperature cranking, pumping and starting characteristics of light and heavy duty diesel trucks using various lubricants. The low-temperature performance of oils with different SAE viscosity grades and base stock type were evaluated. Included are formulations based on conventional mineral, hydrocracked and synthetic base stocks. The results show that lower viscosity grade oils using special base stocks, in particular synthetics, demonstrate improved low-temperature cranking and pumping performance over conventional lubricants. The engine test results are compared against laboratory low-temperature flow, cranking and pumpability tests.