We have had questions regarding the type of oil to use in the winter for your automatic ATVs/UTVs. Here's Honda's response:
2003-2011 TRX650FA/FGA, TRX680FA/FGA, MUV700
Includes Honda Rincon and Big Red
The TRX650 and TRX680FA/FGA models, and the MUV700 have an automotive-style automatic transmission with a torque converter. Unlike cars, however, these models do not use a separate oil supply for the transmission, instead they use engine oil.
The torque converter must be completely filled with oil before the unit will move. Therefore proper engine warm-up is essential to allow the oil pump to circulate sufficient oil through the converter before riding the unit.
Here's why. In operation, engine oil is pumped into the drive side of the torque converter, mounted on the crankshaft, and exits the driven side before continuing through the crankshaft. After sitting, oil in the upper half of the torque convertor drains down. The engine therefore needs to be run for a moment to allow oil to be pumped back into the torque converter before it will operate correctly.
And remember, use the specified 10W-30, or in cold weather, 0W-30, or in hot weather, 10W-40. Note that 10W-40 oil will require a slightly longer warm-up time.