Service temperature according to Hyundai factory instructions for changing automatic transmission oil on a Hyundai Solaris car:
Optimal temperature: 40-50 °C (104-122 °F)
Maximum permissible temperature: 60 °C (140 °F)
If the temperature exceeds 60 °C:
* Wait for the automatic transmission fluid to cool down.
* Change the oil at temperatures below 60 °C.