Ricklee4570

Mine runs at 204 to 209 on the highway with no load.

Indy2015

I've got a '15 with 2.7 and 6R80. It seems to like the 196-203 range the best. I've never seen it above 203, even when pulling a heavy load. No max tow, just the normal towing package.

tcp2

hit 235 on my 16 6r80 up very steep grades at low speed towing 5k lbs.

babock

To me, that's too high. If I see the same, I will dd another cooler. I have a travel trailer that is going to be 6K loaded and a boat that is anywhere between 6K and 7K loaded.

Not too worried about it getting too cold if its true that the tranny has a built in thermostat which is what was being said in the other thread.

RL1990

You have to stop thinking about how it used to be. You need to be worried about too cold not too hot. The fluid's lubrication qualities don't work well at low temperatures. This is why the trucks have a fluid warmer, to get up to temp as fast as possible. If the fluid is to cool you will be increasing wear in the transmission. Mercon LV and ULV are full synthetics and are capable of handling high temperatures for short periods of time. The 10R80 is new but the 6R80 has been a good reliable transmission.

babock

My understanding is that the tranny has a builtin thermostat based on other threads so it can't get too cold.

The only engine that includes a fluid warmer is the V8.

Do you tow at all? If so, how much do you tow and what has your ATF fluid temp gone up to?

RL1990

All engines with the 10R80 will have the warmer. The thermostat and bypass valve can't prevent overcooling if you add an additional cooler. Speaking of that thermostat; my truck is a 5.0 with the warmer. In the winter temperatures it actually runs HOTTER than the summer at 200-205, summer is 190-200. I assume the computer monitors ambient temp and allows the fluid to get hotter before opening the bypass to cooler to prevent overcooling since the ambient temp is cold. Apparently the computer's algorithm also uses ambient temp as one of its inputs to determine when to send fluid to the cooler. In hot weather it must start sending it to the cooler at a lower fluid temperature than in the winter to keep temp in the ideal range.

I towed with it once and didn't pay attention to transmission temperature.

These transmissions are designed to run at higher temperatures than you may be accustomed to. The 6R140 in the super duty also runs at the same temperatures and they tow way more than the F-150. You won't find many complaints on this forum about transmissions overheating. Any and everything that can and has gone wrong on a F-150 can be found here.

Simply put don't try to out think the engineers that designed and built the transmission.

sailorjerry

My 5.0 definitely doesn't run any warmer in the winter, infact during Christmas I spent 4 hours driving on the interstate at -20 below and the transmission temp was 185, about 10 degrees colder than normal.

You should always try to out think other engineers, you might come up with something better, or at least have a lot of fun trying.

Ricklee4570

From what I can tell on my 2017 with a 2.7, there is no thermostat in the transmission. The fluid is in constant circulation. Can anybody verify there is a thermostat, sounds like a lot of guessing going on.

babock

Does the 10 speed transmission even come with the 2.7?