Transmission cooler or not Thread

Get RAS for towing if you aren't going bags or something.

If you are mostly towing and want a regear then 5.29 for sure. That and tranny cooler should be solid. A DD exhaust for general performance wouldn't be. Bad either.

 

That's been my experience too as far as gear v MPG.
I send a trans fluid sample to Blackstone 4 weeks ago and expect the results back any day. I'll post them here.

 

Interesting. What kind of mileage did you get?

R. 4.7 l struggled so bad through South Dakota, Wyoming, Nevada, Idaho, and Oregon lol It struggled the whole way. The best I could do was about 6 and 1/2 mi a gallon.

It SUUUUUCKED! filling up every 2 hours

 

Oh fantastic! I use Blackstone for my Land Cruiser. Well all my Toyotas now the whole fleet.

 

Does anyone know if the 2018 Tundra with the oil cooler for the transmission has the same tranny model number as the 2019 to 2021?

 

Haven't heard of anyone who's has a transmission failure since they removed the cooler in 2019 yet.

 

I believe it does but watch out for 2018. Those had ac issues due to the required change to a different ac refrigerant. That’s the whole reason the integrated trans cooler was gotten rid of in 2019+. Needed the extra surface area previously occupied by the trans cooler

 

Great heads up on the 2018 and no no issues on 2019 - 2021 transmissions is a relief.

 

It 100% depends on how fast I want to go. It will burn a lot of gas if you want it to
Towing my 27' box on wheels at 70 to 75 I get about 7.
If I keep it to 60mph I can do right about 10.

I have never met a hill that the Tundra would not hold the speed I wanted

The other advantage with towing in 4th is that it almost never downshifts at highway speeds. I think that the trans is programed to hold in 4th up to nearly wide open throttle.

 

I have had more than one Tundra without the cooler. Towed, went off road and everything else. So far so good!

 

With this rig 11.4 MPG seems to pop up in hand calculations often. Low 10's if fighting a bad headwind but I've seen mid 12's on 55 MPH highways. Average speed once rolling is about 65. Fly down the hills like I fell down a mineshaft and crawl back up the other side dropping to about 60.

 

All right. Thanks for chiming in. Appreciate the input, perspective and experiences shared!

 

That is a nice unit. You are narrower, shorter and lighter than I am. Once my family is done camping with me, I will be in a smaller unit as well. Here is my setup.

 

In to keep an eye on this thread

I have a '21 and am thinking of throwing a cooler on it at 22K miles

 

I want a cooler on mine but my selling dealer couldn't assure me that I wouldn't void my warranty if there was ever a failure of my transmission. Even if they used genuine Toyota parts and did the install. So, for me it's S4 and drain and fill with my fingers crossed. I have around 34K with 12K of that towing the trailer. It has a GVWR of 6080 but usually scales at 5200 on the axles and 550 tongue weight. The truck is right at 7200 with the back seats out....As long as we don't supersize drive thru meals.

 

Thats the one, most of us have used his kit, it includes all the OEM parts from 2018 and lower trucks along with a setrab radiator and mount that makes it look stock. Others have also went the DIY route ordering all the OEM parts individually and creating their own mount. There is a thread on the cooler kit here that he will post in when he runs deals or has more kits in stock. https://www.tundras.com/forums/genuine-cooling-systems.131/

There is also some threads on here on the DIY route as. https://www.tundras.com/threads/transmission-cooler-bracket.136129/

 

I have done pretty much everything with my 21 2wd V8 on and off road with no cooler added. Never had a problem. That said if you feel you need one then just get it! Its kinda like the oil change interval arguement!

 

I bet you anything by the time your tranny fails, none of those morons are even gonna know or remember if it's aftermarket or not.

 

If it was to fail and under warranty its easy to see the add on and they will question your claim. This info was obtained directly from Toyota as they cut cost and limit liabilty! Rather than argue, I suggest some research before, not after, someting happens.

 

Its not that easy to spot since it used all OEM parts from 2018 and below so it would look just like the rest plus Its also very easy to remove as well if you needed to bring it in for warranty. Fact is though, thr chance you need warranty work on your transmission with in the warranty period with or without a cooler is extremely small, thats why they make the warranty window, to limit them having to fix things on their own dime. Toyota knows the transmission won't fail without a cooler before the warranty but obviously it will last much longer with one.

 

As others have stated, the Genuine Cooling Systems kit is good to go. It’s not cheap but it’s a turn key solution that looks OEM and is significantly more efficient than the older cooler that was quite frankly undersized for towing. I have their old kit with the Improved Racing MHX cooler and it keeps my transmission at 190-195f even when using a lot of lower gears and 4x4 while towing my trailer. Loaded for camping my gross combined weight is right around 11,000lbs and it does awesome.

 

This video does a good demonstration as to why these things generate so much heat in the OD gears.
https://www.youtube.com/watch?v=YM40HOYtLNc
Notice that 4th spins with almost 0 resistance because you are not using any gear reduction or amplification.
Notice how much harder he has to work to turn the trans in 5th and 6th vs. 4th.

This is NOT a bad transmission design. The durability of them and the service record prove it. BUT they are not very efficient at transmitting a lot of power through 5th and 6th. This is why the truck is so quick to downshift.

Compare this with the Allison (another legendarily reliable transmission). Notice two things.
https://www.youtube.com/watch?v=1ByVBBfEXWk
First, how much simpler the transmission is. Simple is not always good but it is simple.
Second, how much effort it takes to spin that trans in OD.

OD gears require a lot of gear on gear work. This requires effort. Effort makes heat.

Some manufactures combat this by using a lower rear axle ratio. What you trade here is heat in the transmission for heat and even higher gear on gear loading in the rear axle. This destroys the gear oil and you get to buy a new gear set.

IMO, you are best to run the transmission in its most efficient state if you are asking it to transmit a lot of power. At that level of power output your engine is not going to get better mileage at lower revs anyway. AND you are lowering all of the forces on the pistons, connecting rods, main bearings etc.

The same is true for a diesel. However, they do not rev very high at all so an OD transmission is needed to get the highways speeds.

 

Seems like a lazy (and 100% predictable) response from a dealer to me. They will not say or write anything that would require anything whatsoever of them in the future.

Would the Magnusson Moss Act not apply here? It is literally just putting the same parts that came on a 2018 on your truck so that it works as originally intended with the tow package.

I put mine on immediately. Granted, it has never been to the dealer for any issues so no one had a chance to even notice it, and I’m out of warranty now.

 

Exactly and I have had mine to the dealer, not for transmission issue, but for a fluid drain & fill, NOT A WORD about it, even after I told them I added a cooler. I wanted them to be aware, so they'd pin it open while doing the D&F.

 

Here is my other pet peeve about this issue.
We are very worried about the life of the transmission so we spend a ton of money on cooling. Is that really the right answer?
Should we do the most work in the gear that is the friendliest to the transmission, that uses the least number of gear sets, that will lower to loading on all of the internal components, that will almost never call for a downshift or a converter disengagement, that generates the least heat?
Sure then engine is running faster. Do we care? Will this engine ever wear out? Are we concerned?
We may get better mileage in a higher gear? Not in my experience.

I can go 75 mph at about 3,300 RPM in 4th gear. I have owned several Asian and European cars that turned faster than that in OD while causing down the highway..... for hundreds of thousands of miles.

 

I see your point and agree. I have done both: I spent the money on the OEM parts and a cooler, and I monitor lockup and limit my transmission to S4 when doing real work or towing.

There does seem to be some kind of general aversion to high RPM—like people are scared of their NA engine making peak power—which I would gently say is irrational.

 

My oil analysis didn't come today but two sample kits did!

There are some very good points brought up in the last page of posts. Temperature of the fluid is only part if the problem. The extra torque passing through the transmission when towing is another one. There's probably not much that can be done to completely eliminate the wear caused by the latter. Doing frequent drain and fills will help but the question remains how much. I'm really hoping to get some insight from Blackstone to see if I'm on the right track with my D&F schedule.
As far as the engine goes, I don't think running an extra 600 RPM is going to do much to harm this 5.7. It's not your old Detroit pushrod, cast iron boat anchor. Keep the oil changed and watch the temperature of the transmission and don't worry about it.

 

When in 4th there are no gears turning so the amount of power you put through the transmission is irrelevant to the heat. This is the only gear that this is true for.

No the extra 600 revs will do nothing to your engine except pump more oil and more coolant…. That seems good

 

Thanks for the video link. That helps explain why I can't positively note a difference in MPG between 4th and 5th when towing.

 

You are welcome.
I think that the biggest reasons that the mileage is no different between 4th and 5th when towing is the amount of horsepower needed is much greater than the amount of losses that come with the engine spinning at a higher RPM. That and the fact that your engine is actually more efficient at making that much horsepower at a higher RPM
The game changes when you unload the truck and your horsepower needs go down. Now you are pumping this engine against a mostly closed throttle. The lower the RPM the better the economy will be in this case.