Hi,
The thermostat is opening too early. It should stay closed until the desired temperature is reached.
As far as the fluid check you can still check it. Keep in mind that ATF expands when it gets hot. So, at 140 degrees, it may indicate the level on the low side, but it should certainly be on the stick.
Check it and let me know what is on the stick.
Take care,
Joe
Friday, March 18th, 2022 AT 7:08 PM