TM 10-3930-669-10 Section IV.  OPERATION UNDER UNUSUAL CONDITIONS 2-12.  UNUSUAL ENVIRONMENT/WEATHER. The  forklift  usually  operates  under  conditions  that  are  UNUSUAL  for  other  forklifts.    Operator  PMCS  instructions  are designed to cover these conditions.  However, operation in extreme heat, cold, or dust requires additional checks and services.  The following paragraphs cover these conditions. a. Operation in Extreme Heat. CAUTION • Operating  during  periods  of  extreme  heat  [ambient  temperatures  above  100°F  (38°C)]  can cause  the  forklift  engine  and  transmission  systems  to  overheat.    Engine  temperatures  above 250°F (121°C) and transmission fluid temperatures above 230°F (110°C) can cause damage to engine   and   transmission   system   components.      Transmission   fluid   temperatures   should   be checked  often  during  periods  of  extreme  heat  to  prevent  damage  to  engine  and  transmission system components. • Gaskets  and  seals  are  more  likely  to  leak  when  engine  and  transmission  system  operating temperatures  are  high.    Engine  and  transmission  fluid  levels  should  be  checked  more  often during  periods  of  extreme  heat  to  prevent  damage  to  engine  and  transmission  components. Checks for leaks around gaskets, seals, and fittings should also be made more often. (1) Check engine oil level (Para 3-6) and operating temperature often for system temperature above 250°F (121°C).  If engine operating temperature is above 250°F (121°C), shut down forklift. (2) Check transmission fluid level (Para 3-9) and operating temperature for system temperature above 230°F (110°C).  If transmission operating temperature is above 230°F (110°C), shut down forklift. (3) Perform operator PMCS more often than normal (Table 2-3). b. Operation in Extreme Cold. (1) Remove all snow and ice from forklift as soon as possible. (2) Prepare forklift for operation in severe cold temperatures according to FM 9-207, FM 31-70, FM 31-71, and FM 21-305 as necessary. 2-43