Mercon LV temps?

[buck91]

Was towing with the F150 the other day and since I don't have the dedicated tow package (thus, not aux trans cooler) I popped the gauge into diagnostic mode to watch the trans temp. Noticed that best case it would hold baout 96C on the highway at 70mph and climb to a max of 100C during frequent acceleration or deceleration. Truck was in tow mode which uses the trans and gears to help with braking and stuff, which works really well but is probably a little harder on fluid.

Anybody know what a safe operating temp is for Mercon LV? I do not tow often, and would like to add a cooler but its just not going to happen for a while.

 

[40Deluxe]

It should be same as the coolant temp

 

[Rand]

I would expect it to be nearly the same as the coolant as there is a heat exchanger there.

Therefore as long as its under 240f I'd feel it was perfectly fine. Higher for mountain climbs etc.

 

[buck91]

Yes, it was pretty much staying dead on with coolant temp.

 

[double vanos]

The PDS sheet shows LV having a pour point of -54F and flash point of 421F. With a viscosity index of 151 it appears to be quite stout for a LV fluid.

My FX4 has the trailer towing package and the temps range from195 to 203 when fully warmed up.

I started swapping 3 qts out every oil change starting at about 60-70k miles. The fluid had no burned smell or discoloration at all. I highly recommend using ONLY Mercon LV fluid as the wanna-be's are also spec'd for use in place of the new Dexon and I have a feeling the formulations differ slightly and, while the non OEM may work, it won't work optimally. Castrol has a Mercon LV / Dex 6 fluid that maybe somebody here has put in a F150 six speed trams and can chime in.
I can buy Mercon LV at my O'Reillys for less than $7 so I'll just stay with the OEM.

 

[buck91]

Good info, double. Interesting to see your truck with the cooler runs about as hot. How heavy do you tow? I was towing maybe 5500lbs.

 

[LotI]

My E450 with the 5R110 runs coolant temps of 193F all year round. The trans temp will be about 180-186 driving level ground at highway speeds in the summer. Winter will creep slowly up to 180F but can take an hour to get there.

Hills will push coolant to a little over 200 but the trans will crest 210. My GVWR IS 14,500# and I'm at about 13,000#.

Coolant temps will rise and fall directly with the load but the trans will lag by minutes. I would bet that Ford is measuring the sump of the trans.

 

[Whitewolf]

Originally Posted By: buck91
Was towing with the F150 the other day and since I don't have the dedicated tow package (thus, not aux trans cooler) I popped the gauge into diagnostic mode to watch the trans temp. Noticed that best case it would hold baout 96C on the highway at 70mph and climb to a max of 100C during frequent acceleration or deceleration. Truck was in tow mode which uses the trans and gears to help with braking and stuff, which works really well but is probably a little harder on fluid.

Anybody know what a safe operating temp is for Mercon LV? I do not tow often, and would like to add a cooler but its just not going to happen for a while.


That temperature range is not a problem at all.

 

[meborder]

The cautionary range (yellow on the dash gauge) is 230-250f. You can rum those temps all day without harm.

The "red zone" is above 250. You can run at temps greater than 250f for periods of 30 min at a time without harm.

If it gets above 250, and wont come down driving it( for more than 30 min), you should pull over and idle the engine unto the temp comes down out of the red. Do not shut it off with the trans that hot.

These temps and recommendations come from a retired ford transmission engineer that hangs out on other forums, so I consider the info to be as good as it gets.

Also the 6r80 has an internal thermostat which doesn't start to open until about 175f, so it will almost always run higher than that if it is driven long enough to get fully warmed up.

Sounds like you are fine for now. Add a cooler as time and funds allow.

 

[MNgopher]

Those temps sound normal for a 6R80 transmission in the F150. I have a 6R60 in my 07 Explorer with the V8, and it runs all day around 180 in normal summer driving, but can creep up to 205+ in certain conditions.

As others noted, there is a thermostat in the unit that doesn't allow fluid to get to the cooler until temps are above 175ish. Certainly a change from the 4R75 in my F150 that runs around 150ish all the time, going above 160 when towing.