The other major Lend-Lease recipient of the M3, the Soviet Union, was even less happy with the tank, considering it undergunned, underarmored, likely to catch fire, and too sensitive to fuel quality. The narrow tracks were highly unsuited to operation in winter conditions, as they resulted in high ground pressures under which the tank sank into the snow. Further, the M3's radial aircraft engine required high-octane fuel, which complicated Soviet logistics as most of their tanks used diesel. In 1943, the Red Army tried out the M5 and decided that the upgraded design was not much better than the M3. Being less desperate than in 1941, the Soviets turned down an American offer to supply the M5. M3s continued in Red Army service at least until 1944.
