Can we trust any manufacturer about anything anymore? (Using my Toyota transmission as an example)

[Oey12]

The owners I have seen showing ATF temps that are too low are those pinning the thermostat open, so that it is bypassed.

If the thermostat is left to operate normally, the ATF temps are fine and seem equivalent to those with pre-2019 Tundras w/ factory cooler. The factory cooler built into the AC condenser on the pre-2019 models is not small.

My apologies but I am not quite following you…

I am not saying that an aftermarket cooler will bring the transmission temperature down too much. All I was saying is that they will be lower than Toyota OEM factory installed cooler tat is on the 2018 and older Tundra’s.

And I didn’t say the OEM cooler is small or cheap. Based on my research aftermarket are higher quality and better performing. However it does not negate the quality and efficiency of the OEM one. It clearly works based off its track record which is why I feel like they just should have left it.

And to your last point: I have two buddies, one had a 2007 5.7 and the other has a 2016 5.7. Both have factory coolers and they consistently run at about 197F (not towing). I consistently run at about 203F.

 

[ctechbob]

I wouldn't say 'all' tow package trucks use an external cooler. Ford uses a water/oil cooler on the 10R80's across the board as far as I'm aware. I know of several of us that have monitored temps and they sit right around 200 even under heavy load. I've never seen mine climb above 210 and that is pulling what most would consider 'too big' (26' Box, ~5700#, 8' Wide) of a travel trailer with my Ranger, in Georgia, in the summer, in the mountains, at highway speeds. The 210 I saw was idling through traffic. As soon as we started moving, it dropped back down to 200.

I suspect the reason many manufacturers are going the water/oil route is that they can bring the trans up to temp a lot quicker, eeking out that tiny little bit of economy. That and it is one less heat exchanger they have to mount in the cooling stack.

I don't think Toyota did it just because they were being cheap, I think they just found a different, perhaps slightly better, way to acheive the same goal as an external cooler.

 

[PWMDMD]

And to your last point: I have two buddies, one had a 2007 5.7 and the other has a 2016 5.7. Both have factory coolers and they consistently run at about 197F (not towing). I consistently run at about 203F.

~200F is what my 2020 runs around town after +10 miles of driving.

As for pinning the thermostat open...I know a couple of owners advocate pinning it open in the summer only but I don't see the point in my application. With coolant temps of 200F and the size of the heat exchanger, I can't imagine there is much of a difference when on the highway with trans temps of 225F. The delta T is low and the area of heat exchange is small. My guess is the heat exchanger is a better transmission fluid warmer than cooler since my engine warms to operating temp very quickly and the delta T between coolant and transmission fluid can be +175F in the winter.

 

[ls1mike]

Now that is a proper transmission cooler! Lots of surface area.
Did you happen to notice how much cooler your transmission runs on average ls1mike?

This was my old 3/4 ton 6.0/4L80E Chevy. I could tow over the passes out West at 60 to 65 in 110 degree heat and not see over 180. Recovery was much quicker than with the stock one. My 2017s cooler is about that surface area from the factory. I regularly tow 8000lbs. So a good cooler is worth it to me.

 

[frankbee3]

That is good information. Thank you!

 

[giskkk]

Sounds like they determined that without the cooler the transmission will make it through warranty, which is all they care about.

I would add the aftermarket cooler. A full-size truck should have one, especially when towing or hauling.

Yep I added the cooler on my 2021 to help with long term transmission reliability.

 

[Tomioka]

Any cooler is worthless if you can't get enough air moving through the cooler in the first place. Having a computer actuated engine fan using various temp and pressure inputs helps keeps temps in control by automatically increasing fan speed no matter what the cooler is. No bi-metal strip actuated fan clutch has the ability to detect trans temp or increasing A/C pressures to quickly ramp up engine fan speed.

Here's my extreme observation: My company flatbed Freightliner M2 with the Allison 2500RDS and Cummins B6.7 has no external transmission cooler. With just a regular water-to-oil cooler like a typical car I never had trans temp go above 200°F and the pneumatic automatic fan clutch kicks in at 220°F keeping things cool.

 

[Chevelle3221]

Yes they took the cooler out but the vehicle is still warranted. If you look at the Tundra forum a guy started selling his own cooler set up for big bucks claiming the truck needed it. However, he wanted big bucks for something one with some ability can do for alot less. People will say they follow the trans temp but these use their own guages and the truck does not have a trans temp guage from the factory. Like anything else there are 2 sides to a story and in the middle the truth! I have a 21 Tundra that I tow with here in Fl. I also have and extended warranty from Toyota that takes me over 100K and it was purchased at a crazy price. If you think you need it get it but buy a B&M or Hayes STACKED cooler kit as its an easy install.

 

[jeepman3071]

My experience is that most manufacturers engineer things to get through warranty. Not meaning that it is designed to fail right after warranty, but from a manufacturing efficiency standpoint. It doesn't pay off for them (besides maybe reputation) to overbuild something. When they overbuild, they are losing money. Toyota has determined that the Tundra can make it through warranty without the cooler, for MOST and probably all customers. The long term results are impossible to know upfront, and the difference in transmission temps for the small percentage of truck owners who actually tow could have a marginal impact over the long term, which would be irrelevant for a vehicle that changes owners a few times. By the time the transmission fails (if it fails), the truck is likely 10+ years old and on at least its second owner.

With that said, I usually base my maintenance habits on the manufacturers recommendation, but also take into account my own use case and experiences shared by others.

If I owned the truck in question, and planned on towing and owning it out of warranty, I'd opt to install a cooler as well as changing the fluid every 30k. If I wasn't towing and/or trading it in within warranty, I'd simply change the fluid at the specified interval.

 

[wpod]

Why is it seemingly that it's always coolers that seem to be cut?

Drain plug on the torque convertor and differentials.