well basically ive noticed that when its below 35 degress the torque converter doesnt lock up in third and o/d. is this normal? when the search function was enabled i remeber reading it wont lock up until it reaches 100' F? seems to be the case. i had my dad (firestone) change the fluid at 30000 miles. truck has 50000 on it now. just noticed it this winter. it didnt seem to do it in with the factory motorcraft fluid. i asked him about what style fluid it is. he says its a synthetic based fluid. he researched it and said that he only puts in what the manufacturer recommends. thanks for the help fellas!

 

Perfectly normal for the 4r100

 

Mine does the same thing. No O/D until fluid warms up slightly. I once owned a Toyota Motorhome that did the same thing and it stated this in the owners manual.

 

Mine does it too.......another reason why I never get in too big of a hurry after the truck has been sitting for awhile. It takes a few minutes before it shifts into overdrive, longer when it's cold out.

 

When I started my truck up this morning the trans fluid temp was 10 degrees as verified by my scangauge 2. (Sweet little unit)

Mine will hold the rpms until the engine warms up to a certain points. 100 deg sounds close. I usually let my truck warm up a bit before taking off.