Let’s talk transmission temps

[BH1989]

I have a 2009 Yukon Denali XL that I tow our boat with. Boat is 3600lbs dry and trailer is roughly 1500lbs so I am at 5100lbs. My normal trans temps with no boat or trailer are usually around 160-170 degrees F in the summer. I have noticed when towing the temps are obviously higher. I am usually around 190-200 Degrees when towing in the summer. I am in Illinois so roads a relatively flat and I tow about 30 miles each way on the weekends. There have been a few times trans temps have gone up around 205-210 Degrees F. They usually come back down over time but is there anything I need to be worried about?

My other concern is I am going to be towing from Illinois to Missouri roughly 450 miles, in May. The Yukon does have the external trans cooler, but it looks small. Should I look into a larger cooler?

Should I look at draining the trans fluid and swapping with something different?

Thanks for the help

 

[swathdiver]

I have a 2009 Yukon Denali XL that I tow our boat with. Boat is 3600lbs dry and trailer is roughly 1500lbs so I am at 5100lbs. My normal trans temps with no boat or trailer are usually around 160-170 degrees F in the summer. I have noticed when towing the temps are obviously higher. I am usually around 190-200 Degrees when towing in the summer. I am in Illinois so roads a relatively flat and I tow about 30 miles each way on the weekends. There have been a few times trans temps have gone up around 205-210 Degrees F. They usually come back down over time but is there anything I need to be worried about?

My other concern is I am going to be towing from Illinois to Missouri roughly 450 miles, in May. The Yukon does have the external trans cooler, but it looks small. Should I look into a larger cooler?

Should I look at draining the trans fluid and swapping with something different?

Thanks for the help

Many will say to upgrade the external cooler. Those temps are nothing to be alarmed about but something you may not be aware of is fluid life. If you are towing that regularly, I would change it every 36K miles at most, maybe even sooner after seeing the results of some oil samples.

Is your truck AWD or RWD?

 

[1BADI5]

Heat is the killer to all ATs.

I went with the Tru Cool 40k cooler in addition to the OEM cooler. I also installed the B&M deep aluminum finned pan which holds an additional 2 qts of fluid.

The highest I have seen my trans temps are 138-140* and thats while driving it hard.

 

[89Suburban]

Bypass the factory radiator cooler and add a trucool. Lower temps don't mean shit for a transmission, you can run 60 degrees if you want. It's the higher temps you want to keep down.

 

[1BADI5]

Bypass the factory radiator cooler and add a trucool. Lower temps don't mean shit for a transmission, you can run 60 degrees if you want. It's the higher temps you want to keep down.

I'd love to see that 60* set up

 

[BH1989]

Many will say to upgrade the external cooler. Those temps are nothing to be alarmed about but something you may not be aware of is fluid life. If you are towing that regularly, I would change it every 36K miles at most, maybe even sooner after seeing the results of some oil samples.

Is your truck AWD or RWD?

The truck is AWD, I check the fluid regularly and still has good color and doesn't smell burnt. Last year was the first year of towing. This will be the second year and it will be going from Illinois to Missouri once then only be towed again if I need to move it.

 

[Bob2C]

I switched tranny to AMSOIL SIG early on and after my first towing stretch of about 1500 miles I just did a quick fluid exchange through the dipstick. Did it cold so it’s an even exchange with new fluid. 5.5 out 5.5 in. Yeah it might be overkill but it’s cheap insurance IMO.


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[89Suburban]

I switched tranny to AMSOIL SIG early on and after my first towing stretch of about 1500 miles I just did a quick fluid exchange through the dipstick. Did it cold so it’s an even exchange with new fluid. 5.5 out 5.5 in. Yeah it might be overkill but it’s cheap insurance IMO.


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That’s pretty good I can only get about 3 1/2 quarts swapped through my tube. Also saw on a video that @Rocket Man posted that the oil level inside the pan should be at the gasket mating surface and that most factory dipsticks full marks are wrong. So they say anybody who drops a pan check that full mark location and fix it while the pan is off.

 

[Bob2C]

That’s pretty good I can only get about 3 1/2 quarts swapped through my tube. Also saw on a video that @Rocket Man posted that the oil level inside the pan should be at the gasket mating surface and that most factory dipsticks full marks are wrong. So they say anybody who drops a pan check that full mark location and fix it while the pan is off.

Interesting. I take the oil right to the top of the fill line when the temp is 190. I know anywhere is ok within the checkered area but it’s my OCD I guess.


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[wsteele]

Many will say to upgrade the external cooler. Those temps are nothing to be alarmed about but something you may not be aware of is fluid life. If you are towing that regularly, I would change it every 36K miles at most, maybe even sooner after seeing the results of some oil samples.

Is your truck AWD or RWD?

Totally agree.

I have a transmission cooler as part of my setup and normal towing temps with heavier loads (like 5,000 lbs) are 200 degrees. It will creep up to 210 occasionally if I am towing on a warm day in hilly country. It seems very correlated to engine temps, as the engine temp climbs a little, the transmission temp will follow.

Definitely change your transmission fluid regularly if you tow a lot (like every 30-40K miles). The color change will tell you a lot, if you watch it. It gets darker with use.