Oil temp concerns

[SummitJim]

So we have a new 2020 F250 with 6.7 L diesel and 10 speed transmission. Next month we will be towing our 320MKS (about 13,000 lb loaded) to Phoenix from Northern California. So far the engine and transmission oil temps range up to about 190 degree but we will be climbing the Grapevine and then running I-10 in Arizona where the outside temps may hit or exceed 100 degrees. I don't plan to run the engine up to its maximum ability anyway but I'm wondering 1) should I just let the truck do what it wants in tow/haul mode, or manually gear down a bit more on that big hill. And 2) how hot can the transmission get before Ishould be concerned? Should I expect issues, or just a happy truck?
Thanks.

[bertschb]

...should I just let the truck do what it wants in tow/haul mode, or manually gear down a bit more on that big hill. And 2) how hot can the transmission get before Ishould be concerned? Should I expect issues, or just a happy truck?

I have a 2020 F-350 with the 6.7 and 10-speed and I've pulled my 15,000lb Solitude over the Grapevine on 100 degree days a few times. My advice? Put the truck in tow/haul mode and enjoy the ride! Your truck will pull your RV effortlessly.

One thing you should know is the new 10 speed runs quite a bit hotter than the old 6 speed but that is normal. You may see transmission temps in the 215-220 range while climbing the Grapevine.

I would expect zero issues. The new powertrain is awesome! Enjoy!

[huntindog]

Just because it is "normal", doesn't mean it is good for the fluid. The GMs and Rams run a lot cooler.... The thing about fluid though is it doesn't care what brand of truck it is in. Just how hot it gets.

[jleonard]

220 F should not hurt the oil. When I was involved with testing automotive components we heated the oil to 240 which supposedly was the max. it should be before it starts to degrade.
I'm not an oil expert but this was the information we were given by Ford at the time.

[Digger1222]

My 2020 f250 7.3 with 10 speed will heat up to 221 and then a cooling cycle kicks in and drops it like a rock to about 205. Then the cycle starts over again with a slow and gradual climb up to 221 and back down. This is towing a 2600 RB in just slight rolling hills. Doesn’t matter if it’s 35 degrees out or 95. It will even go up to 221 driving unloaded in 10th gear cruising down the flat interstate at 75mph at 45 degrees with light rain. Just takes longer to get there but it will. Dealer said that’s exactly what it should be doing.

[bertschb]

...then a cooling cycle kicks in and drops it like a rock...It will even go up to 221 driving unloaded in 10th gear cruising down the flat interstate at 75mph at 45 degrees with light rain.

That's interesting. I don't think I've seen mine go much above 200 when driving empty but then again, I don't watch it as closely as when I'm pulling hills while towing. Also, my temp doesn't drop while pulling a hill towing my RV until the road starts leveling out. The temp gradually increases as I start climbing the hill then stabilizes until the road levels off then the temp starts dropping. I'm pulling twice your weight so maybe that has something to do with my temps being more stable.

[Digger1222]

I have yet to tow the RV up a big hill. Only have towed it here in Nebraska. We’ll see what happens this fall with our trip to Colorado.

[huntindog]

220 F should not hurt the oil. When I was involved with testing automotive components we heated the oil to 240 which supposedly was the max. it should be before it starts to degrade.
I'm not an oil expert but this was the information we were given by Ford at the time.

If the fluid is 220 in the pan, then it will be a lot hotter than that as it exits the tranny enroute to the cooler.

[DECelt]

My 2020 f250 7.3 with 10 speed will heat up to 221 and then a cooling cycle kicks in and drops it like a rock to about 205. Then the cycle starts over again with a slow and gradual climb up to 221 and back down. This is towing a 2600 RB in just slight rolling hills. Doesn’t matter if it’s 35 degrees out or 95. It will even go up to 221 driving unloaded in 10th gear cruising down the flat interstate at 75mph at 45 degrees with light rain. Just takes longer to get there but it will. Dealer said that’s exactly what it should be doing.

Same with my 2017 6.7. They are designed to run at these temperatures...it isn't an issue. Our last Colorado trip was in extreme heat up steep mountain passes and towing 14,000 lbs. No worries. Fan kicks in at about 220 and brings things down to about 205, and the cycle continues. My normal transmission temps are right about 200....flat roads and no engine/transmission stress. Enjoy the trip. It is an exceptional engine and transmission.

[Redapple63]

I can completely understand coming from the 6 speed. My 2019 Duramax with the Allison typically runs 165 empty, 180 or so under heavy load, maybe really hot for me is around 190. Could certainly understand coming from an older truck that ran so much cooler. Seems the new 10 speeds run hotter. Not sure if that is the same for the GM vehicles. I know the 10 speed was supposed to be a joint Ford/GM venture, but I also heard that each decided to implement their own firmware which could make the same mechanicals vastly different )my perspective from owning three GM’s with Duramaxes, never owned a Ford.


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