Something else to think about... Transmission failures in these trucks are practically unheard of. Sure, it can happen... but it's rare. Very rare. It's not a ticking time bomb that you need to be all nervous about.

Good luck.

True, when stock. I figured with the URD SC putting out more power, and that when I tow, it's usually through the mountains, it certainly couldn't hurt to have one on there. I also intend on moving out of the rust belt back to a much warmer climate, where if you tow at all you probably could do well with a tranny cooler.

I watched the tranny temps on the drive home from work the other day. 20F ambient temp and never topped 60mph. Cruising at 40-45mph it stayed between 90-100F, with a high of 105F when I accelerated hard (rpms to 4krpm before shifts) to get around a moron. 105F quickly dropped back to 100F

Which of the X-Gauge codes have you been using to monitor ATF temperatures? I have a ScanGauge II but haven't been successful yet.

Using the iDataLink Maestro-RR through the Kenwood DNX995s I installed. I had to validate the PID's first to get it to recognize the Tranny temp, but it gives it real time with the gauges page selected.

Unless you have reason to believe your trans temps are abnormally high I would avoid it. Any time you add components you add something that can fail. Also, as stated earlier, it good to get your transmission up to operating temperature. A cooler without a thermostat might keep your temps below target and, while better than over heating your transmission, is almost as bad as routinely not letting your engine oil get up to temp.

The scangauge ii works fine for both torque converter and transmission pan, do you just need the codes?

I have far more faith in the Toyota engineers who built this thing than I do in some anecdotal stories from bros on the internet

Wouldn’t be something I would spend money on if I was in your position

But then again, now I’m a bro giving you an anecdote

I remember I used either the 3rd one on the list or the 4th one, I don't remember exactly. I know the first 2 on the list didn't work on my '18 OR

>> TOYOTA – LEXUS – SCION

I looked for the tranny pan temp since the torque converter is too erratic to be close to be correct.

If towing at/near the max consider installing a dedicated atf temp gauge. The bullet clamp on sensor is typically accurate enough. Check manufacturer guideline for in city heavy towing. Some manufacturers recommend going to neutral at long lights or train crossings. Be sure to kick down a gear while descending long grades. Your vehicle service brakes should be considered. Hot brakes can liquify. This is really dangerous. Engine braking on long grades keeps the service brakes cool and ready for an emergency. Cold brakes are good for maximum emergency braking.

Install your brake controller where it's easily reached. The brake controller has an emergency over ride in case of Wag the Dog. Wag the Dog is when the trailer takes control. This is really bad. Activating the trailer brake control and not touching service brakes allows the trailer to regain balance and fall in line behind tow rig. Do not install brake controller at bottom of dash or in the knee bolster area. You either can't reach in an emergency or will fail to walk in an accident.

Go slow. The speed limit is the maximum speed.

I carry an infrared heat gun to occasionally check tire, brakes and hub temps. Expect the sun side of the vehicle to be 10deg warmer (+/-). Because of my diesel exhaust brake my service brake temps increase by 10 deg after stopping on a long grade. You can probably expect an easy 50deg service brake temps increase on a gas vehicle.

Toyota was the first truck manufacture to provide a accurate tow rating for there truck line. The other truck manufactures had no real Standard of what they could actually tow in the worst of conditions. Out west we have some of the most brutal towing conditions anywhere. Long grades in high heat. The Grape Vine on I-5, The Cohen pass on I-15, the 7 mile grade west bound out of Needles Ca. The Baker grade in summer will destroy a transmission. Baker is the gateway to Death Valley so you can imagine what this is like in August .In So Cal its usually a five hour drive to anywhere you would be towing something.
In recent years the auto industry adopted the FCA's Arizona proving grounds in Yucca. This is east of Bullhead city AZ on Hwy 68. This is now the standard for towing ratings for the truck industry. SAE J2807. The manufactures and Auto Magazines use this facility for testing trucks and SUV's.The high heat and long grade gives them some of the worst case scenarios for towing.
Motor Trend magazine Issue January 2019 page 70 tested the truck of the year here.
The 4runner is a great truck but it has its limits. Towing is one of them. As long as you don't tow over the recommended limit you should be OK. But if you live and tow out west a trans cooler would not be a bad Idea. Some one also mentioned a T stat in line with the trans cooler. Good idea if you live some place where it gets cold. This will keep your trans at a optimal operating temperature.

Everyone has to use the SAE rating now

JHguth, You are correct its SAE J2807

Whats the highest you've had the trans temp get? Curious why you are considering a tranny cooler.

We have ambient temps of ~130F in our summers, and I hit ~190F trans temps on highway easy. In the dunes, I'm easily beyond 210F on trans temp. But we don't usually offroad during summer time..

Winters I'm usually around 160F trans temp (ambient temps ~70F). Fully loaded truck on extreme drives I hit ~185F trans temp. I noticed that driving beyond 85mph from some time the trans temps rise quite a bit.

modded and heavier truck, but don't tow anything.

It was ok but I was having issues with the setup. I gave up on it and bought a 06 GTO for speed.

Thanks, I entered both the 3rd and 4th one and got readings, same number. This was without the engine running, so they could be from two different sensors (pan & TC). I'll find out tomorrow morning.