Cummins12V98

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4x4ord wrote: Cummins12V98 wrote: Trans fluid life is directly related to fluid temps. I would like to hear the driving type at that temp.
Does transmission oil last longer at 160F than at 192?
From the charts I have read yes.
My AISIN runs 165 on the highway even over 100 degrees ambient. Towing 35k combined 165 up to 172 even at the top of a several mile 6% grade with temps in the high 90’s one specific time coming into Pahrump, NV.
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4x4ord

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ksss wrote: 4x4ord wrote: Cummins12V98 wrote: Trans fluid life is directly related to fluid temps. I would like to hear the driving type at that temp.
Does transmission oil last longer at 160F than at 192?
Amsoil used to have graph that showed tranny fluid life at different temps. I don't know that is that drastic going from 160 to 192 but I think the moral of the story is the hotter the fluid the less longer it lasts.
I think you're right, however, if Ford has designed the transmission to run hotter they may also spec a synthetic transmission fluid to withstand the hotter temperature. I really don't know much about it. The fluid life of the 6r140 is 150,000 miles.
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Grit dog

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^That all makes sense and I'm generally a lower temp is better fan too, especially for transmissions.
However, I think some of the newer transmissions are set to run a bit warmer. For instance my 2016 Chevy work truck runs 190 +/- from the time it reaches operating temp until you shut it off. Even under moderate load, the temp is pinned pretty close to 190. I can only make it get hotter by maxing it out uphill with a big trailer.
"Yes Sir, Oct 10 1888, Those poor school children froze to death in their tracks. They did not even find them until Spring. Especially hard hit were the ones who had to trek uphill to school both ways, with no shoes." -Bert A.
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B.O. Plenty

Minnesota

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specta wrote: blofgren wrote:
I once said I'd never own a Ram too; bought the truck in my sig 6 years ago and am a very happy camper.
That said, we love our 2001 GMC Yukon too! ![biggrin [emoticon]](https://forums.goodsamclub.com/sharedcontent/cfb/images/biggrin.gif)
I can promise you that I will never own a Ram or any other Chrysler product. X 2!! I've tried to own one 3 different times and ended up really disappointed with their lack of quality each time. I won't be fooled again.
B.O.
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steve-n-vicki

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It was about 50-50 city driving and open highway, when I started the test drive the fluid was at 42° and as the engine was coming up to temperature the transmission temperature was almost matching it exactly, I was getting concerned until it stabilized at 192 and it did not climb anymore,
I pulled one grade that generally should’ve heated the transmission up but all the truck did was drop one gear and the 7.3 pulled the hill in ninth and was accelerating And the trans temperature stayed at 192
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spoon059

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ford truck guy wrote: SO....
It happened. and it's my wife's fault ![biggrin [emoticon]](https://forums.goodsamclub.com/sharedcontent/cfb/images/biggrin.gif)
And...?
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Cummins12V98

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If the trans cooling system is designed to keep the temp near 190 even at full GCVWR on a hot day and long 6% grade all will be well.
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Travlingman

Jonesborough, TN

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Cummins12V98 wrote: If the trans cooling system is designed to keep the temp near 190 even at full GCVWR on a hot day and long 6% grade all will be well.
Well, it isn't. They are designed to run around 220 to 230 under load. The cooling fan isn't programmed to hit full until over 250 degrees.
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Cummins12V98

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Travlingman wrote: Cummins12V98 wrote: If the trans cooling system is designed to keep the temp near 190 even at full GCVWR on a hot day and long 6% grade all will be well.
Well, it isn't. They are designed to run around 220 to 230 under load. The cooling fan isn't programmed to hit full until over 250 degrees.
If this is true it's NoBueno in my book. The only time my trans has seen 190 and not sure if it has even hit that is in city driving in hot weather.
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Cummins12V98

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Travlingman wrote: Cummins12V98 wrote: If the trans cooling system is designed to keep the temp near 190 even at full GCVWR on a hot day and long 6% grade all will be well.
Well, it isn't. They are designed to run around 220 to 230 under load. The cooling fan isn't programmed to hit full until over 250 degrees.
If this is true it's NoBueno in my book. The only time my trans has seen 190 and not sure if it has even hit that is in city driving in hot weather.
Several miles of 14% grade locked in 2nd gear my trans temp was 172, ambient 74, coolant 210 and combined at 33k.
Seems very odd that a more modern trans isn't staying anywhere near as cool.
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