Installing an aux transmission cooler this weekend...keep OEM cooler or bypass?

As the title says, I'm installing a aux transmission cooler and curious if I should keep the OEM cooler in play or bypass it with the new cooler?

 

There was a thread about this same thing somewhere else around here that a dude did. He originally piggybacked the new one to the oem one then I think he ditched the oem one and just ran with the bigger one

 

The only advantage the OEM has over aftermarket is that the brackets on it line up with the holes making it easy to install.

If you are going to the trouble of adding a bigger thicker aftermarket cooler, making holes and brackets, I don't see the point of keeping the stock one. It would just be taking up frontal airspace and adding complexity to the system increasing chances for leak/failure. If you want more cooling power, just buy the biggest aftermarket stacked plate cooler you can fit and get rid of the OEM.

 

Definitely ditch the OEM cooler. I think the bigger question should be whether to bypass the ATF reservoir in the radiator. It's primary advantage is to warm up the ATF faster during start-up - I really can't see any other advantage. I see two disadvantages of passing ATF through the radiator: one, if the radiator overheats, so will the ATF; and two, an internal rupture can cross-contaminate the coolant and ATF - ask Nissan truck owners how that feels like. If in warmer climates, I would definitely recommend bypassing the radiator. It's a consideration in the 'colder' states. If you do bypass the radiator, you can always re-route the ATF through the radiator during the cold months.

 

A quick copy and paste from the A750E transmission post

There are some good links in the post that may help you decide what to do .
Lets have a peek at what transmission coolers do
TRANSMISSION COOLERS
If you do not have a transmission cooler on your truck and you plan to tow or haul heavy loads or you are in heavy stop and go traffic and use 4X4 low a lot , consider purchasing a cooler . The cooler thats built into your rad is designed to cool the transmission with the weight of just the truck by itself .When you are in 4x4 low , your torque converter is usually in the stall stage and creates a tonne of additional heat .You dont have much air flow going through your rad when you are in low range 4x4 .
160 - 200 are considered normal temps providing your engine radiator is functioning properly . If your engine overheats , your transmission will also overheat
Normal fluid temperature in transmission to be 175 deg. F.

Rate of oxidation to double for each temperature increase of 20 deg F above normal (175 deg F). As oxidation rate doubles, useful life of fluid is cut in half.

At 175 deg F life is 100,000 miles
At 195 deg F (20 deg above 175) life is 50k miles
At 215 life is 25k miles
At 235 life is 12k
At 255 life is 6,250
At 275 life is 3,000
At 295 life is 1500
At 315 life is 750

At temperatures much above 300 deg F the metals in the transmission will tend to warp, twist etc. high temperatures causes the formation of varnish deposits which impair or pre vent transmission operation.

At a fluid temperature of 415 deg F fluid life is 30 minutes!

Source: Empire Lubricants Inc.
Consider a scan guage http://www.amazon.com/ScanGauge-Comp.../dp/B000AAMY86
Here is the best information for the scan guage http://www.tacomaworld.com/forum/2nd...-pressure.html

Ultraguage is now offering transmission temps http://www.tacomaworld.com/forum/2nd-gen-tacomas/318340-ultragauge-transmission-temp.html

You could also use the Torque app with an Android phone as a cheap alternative to watch your temps http://www.tacomaworld.com/forum/per...d2-reader.html


A picture heavy write up showing a manual gauge install
https://www.tacomaworld.com/threads/trans-temp-sensor.456998/#post-13594000

$84 B&M 80212 Transmission Temperature Gauge Kit

https://www.amazon.ca/80212-Transmission-Temperature-Gauge-Kit/dp/B0002A596I


This is how Low Pressure Drop technology works::
When Automatic Transmission Fluid (ATF) is cold it is viscous. The unique Tru-Cool design allows the colder, thicker ATF to flow more efficiently through two open bypass channels positioned at the top of the cooler. As operating temperatures increase, the ATF becomes hotter and thinner, It's then directed through the core where it is cooled. Tru-Cool's highly efficient cooling technology combines improved protection against lube failure with optimal heat transfer.
http://www.amazon.com/Long-Tru-Cool-.../dp/B005XZXB1M
Long Tru-Cool Oil Coolers offer advanced cooling protection for many towing applications. The advanced technology out performs TUBE & FIN Designs, Delivers up to 15 times less flow restrictions, 30% more cooling delivers maximum heat transfer, Self-Regulating for maximum lube flow protection through start-up, varied temperatures and driving conditions, heavy loads and towing.
Here is Toyotas fluid flow guide ...Look at page 8 on this PDF http://www.toyotatundraforum.com/pdf/A750E.pdf
And here is a guy who recently installed a cooler correctly http://www.tacomaworld.com/forum/1st...agram-pic.html

cooler and fan install http://www.tacomaworld.com/forum/2nd...n-install.html

HERE is the Tacoma World Towing Bible https://www.tacomaworld.com/threads/the-tacoma-towing-bible.4031/

CAN YOU OVER COOL ? Yes . Transmissions are designed to operate at 170ish . There are demulsifiers in the fluid to assist with internal condensation but you still need the steady heat to bake that water off . If installing a cooler , ask yourself what plans you have for the cooler during the winter months .

When you first start your truck in the morning , the transmission uses the heat provided by the engine to warm the transmission .
This results in better fuel economy as well as improved transmission shifting .
With this said , I will always recommend using the factory in line radiator and then place the cooler after the original rad .
There are exceptions to this rule mind you . The strawberry Milkshake effect , a former transmission failure causing the internal rad cooler to plug up or you simply live in an extremely warm area

 

I installed the B&m version and dropped temps by an average of 20 degrees Celsius. Remove the factory and reuse the mounting point and hardware except for one. Ask get yourself an in line magnetic atf filter. Fuck the scan gauge. Get a Bluetooth Odb reader and hook it up with your phone. Use this...

And you can now read atf temps.
I'll take some pics of the install a little later.
Sorry just saw you have a 2012. In the same thread I quoted someone also made a formula that works with 2010+

 

I added one last month (write up not done yet), and kept the OEM for the time being. I decided to go big or go home and put in a HUGE Long Tru Cool #4590 which made an amazing difference when towing my Travel Trailer in the ADK's - a full 30-40 degree drop. I maxed out at 201 in the mountains where last year I maxed out at 240 or so. Generally there was a 20 degree max difference between my TC and pan temps under heavy load, otherwise it was a 2-3 degree difference. I have to find the screenshots on my other device for standard temps (can't remember them right now). The Torque screenshot was under load on flat roads. Worse comes to worse if it's too cool for the NYS winters I'll just bypass the stock cooler by moving the lines.
Edit: and thanks to @gearcruncher for his discussion and info leading up to the install.

 

I think I'm going to keep the factory cooler and route through the radiator. I use an ultra gauge to monitor temps so I'll run it this way and monitor temps for a bit. This winter I may bypass the OEM cooler and radiator and see how quickly it can build up heat.

Busy weekend with family, house projects, and a puking kid last night cut into my garage time...just have to run the lines then I'm good to go. I'm going to send a sample of the ATF to blackstone...I'm curious to see how the report comes back. This fluid has 15k miles on it and had been over 230f for 75 or so miles total, with a couple of spikes above 240f.

 

Kept my stock cooler and added this one. Used 4 rubber coated hose clamps to keep hoses from rubbing. Lost 25 degF ATF temp going up Saluda in NC towing camper.