Transmission Temp

[volpe30]

I'm hoping there is someone on here who can answer this question with documented or first hand knowledge and facts. I've been reading threads related to transmission temps on the 5th gen. I have a 2016 that I use to tow an Xventure XV-2 trailer. When loaded it weighs around 3,000-3,200 lbs, well below max towing. In the summer I will have days where I'll have temps regularly above 200 degrees for most of the day, and when going uphill regularly get into the 230's and low 240's. I'm getting my readings off of a Scan Gauge II. Even going up the hill to my house in the summer, without the trailer, I'll easily get into the 180's. Reading some of the threads on here had me concerned as many state that those temps are unacceptable and potentially damaging, and therefore find it necessary to install a stand alone transmission cooler. But last week I had my truck in for scheduled service (it's still under its included service schedule) and I asked the service manager what it would cost to do a drain and fill on the transmission. He asked me why I would want to do that. I explained my concern and he said I don't need to worry about it. Maybe, he said, to be conservative, I might want to consider it at 60,000 miles, but even that he said probably was being overly cautious. I'll add that last week I was traveling for work and my rental car was a new Dodge Charger. The Charger had the ability to pull up the transmission temp. Once warmed up the transmission on that car was consistently between 200-220 degrees. I've also seen the charts like the one below.

It's my understanding that there are a couple of places that pick up the transmission temp. I'm wondering if the Scan Gauge reads it at the hottest spot? I do notice that it is very sensitive to spiking and dropping, especially when the torque converter unlocks and locks.

So, I guess I'm wondering if things are different with modern sealed transmissions where charts like the one below are no longer accurate. Are the temps I'm getting nothing to be concerned about? It's my preference to keep the engine as stock as possible. It's just my belief that it is in that form that it is the most reliable and that introducing more lines introduces more potential areas of failure. I should note that I keep it in S4 when towing to try and keep the torque converter locked as much as possible.

Sorry for the lengthy explanation.

175°F = 100,000+ miles
190°F = 90,000 miles
210°F = 55,000 miles (Pressure Drops)
230°F = 25,000 miles (Valves Stick)
250°F = 17,000 miles (Varnish Forms)
270°F = 4000 miles (Seals & Clutches Burn)
300°F + = TRANSMISSION FAILURE

 

[e60ral]

the scan gauge can read both the torque converter and the pan. the torque converter will fluctuate but the pan temp is pretty steady.

go ahead and install the cooler you were considering, you don't want to be at those 230-240 temps very long

 

[(none)]

That chart is old and really isn't too relevant. Most modern transmissions are maintain 200-250F. Most with secondary coolers (air to oil) have a thermostat to keep the trans temp above 190F or so.

That being said, i still try to keep mine as low as possible...

If you are getting a lot large fluctuation, you are probably reading temp from the TC outlet instead of the actual pan temp. The pan temp changes are much more gradual.

 

[WallyT4R]

I agree that those temps are a concern. I bought a cooler but have not installed it yet. I tried to get the dealer to install it but they said it would void the warranty which is ridiculous in my opinion since it will actually help the transmission survive longer. Anyway, despite the warranty bs, I plan on installing the cooler at 30,000 miles (at 14k now) then have the dealer flush the trans and put it to the correct level at that time. I don't care what they say, the cooler you can keep the trans fluid, the better it is for the trans long term.

 

[wcjeep]

Your Temps look concerning. Is there a severe duty maintenance schedule? Follow that.

I would also upgrade the transmission cooling.

 

[e60ral]

Your Temps look concerning. Is there a severe duty maintenance schedule? Follow that.

I would also upgrade the transmission cooling.

There is, you'll have to argue with the dealership to get them to follow it

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[FrenchToasty]

Going up a little mountain last Friday, not towing and actually driving very lightly, I saw my tranny temps at 190-219. First time actually paying attention to the temp as I made the climb. I don't really tow, but I do gobi load often; I did a full fluid swap two weeks ago (68k) and I'm really glad I didn't wait. Was the old fluid TOAST? No, but it wasn't red and didn't smell crisp as the new fluid. I also ditched the WS fluid and went to amsoil! Lifetime fluid my ass

 

[sbronemann]

Going up a little mountain last Friday, not towing and actually driving very lightly, I saw my tranny temps at 190-219. First time actually paying attention to the temp as I made the climb. I don't really tow, but I do gobi load often; I did a full fluid swap two weeks ago (68k) and I'm really glad I didn't wait. Was the old fluid TOAST? No, but it wasn't red and didn't smell crisp as the new fluid. I also ditched the WS fluid and went to amsoil! Lifetime fluid my ass

Can't go wrong with Amsoil! Will be switching our 4Runner to Amsoil as well when it needs a fluid change. Will probably do it at about 50k.

 

[wfo9]

The temps will mostly follow the coolant and go up from there. S0 190 is pretty much steady state over run time. You need to learn to shift if properly (manually) to keep the heat down.

The converter being open will heat it up dramatically. Hold lower gears and you will get much lower temps with the TC locked.

Maybe talk to the scan gauge people and see if they can provide information about displaying the TC status. There is a PID for it and it can be viewed with TIS.

The fluid should be fine for at least 70k with extreme towing... 100+k with non towing use. I would not run anything but Toyota fluid. Seen to many problems with anything else in these transmissions. Same with the coolant.. just pay for the right stuff that is very proven (and don't trust a Toyota dealer to put the right stuff in LOL). I see no point in changing it without dropping the pan and also changing the filter. That is why I plan to wait until 100+k. 150 is probably fine.. people over maintain these things like crazy...

 

[volpe30]

The temps will mostly follow the coolant and go up from there. S0 190 is pretty much steady state over run time. You need to learn to shift if properly (manually) to keep the heat down.

The converter being open will heat it up dramatically. Hold lower gears and you will get much lower temps with the TC locked.

Maybe talk to the scan gauge people and see if they can provide information about displaying the TC status. There is a PID for it and it can be viewed with TIS.

The fluid should be fine for at least 70k with extreme towing... 100+k with non towing use. I would not run anything but Toyota fluid. Seen to many problems with anything else in these transmissions. Same with the coolant.. just pay for the right stuff that is very proven (and don't trust a Toyota dealer to put the right stuff in LOL). I see no point in changing it without dropping the pan and also changing the filter. That is why I plan to wait until 100+k. 150 is probably fine.. people over maintain these things like crazy...

Thanks for the feedback. I have a friend that is a tech/mechanic that used to work for Toyota and is now at Honda, and another friend who is a tech/mechanic at a Lexus dealer. Your take on it pretty much lines up with theirs. They keep telling me to stop worrying about it and to only be concerned if the temps get and stay above 250. I also found the below video this morning which basically says "normal" transmission temp is 10-20 degrees above engine temp. My scan gauge has my engine temp consistently between 185-190. So 200-210 would be "normal" for transmission temp. Further, the guy states that you only need to be concerned that there is a problem when the transmission temp gets to 250-300 degrees or warmer. That video is here: https://www.youtube.com/watch?v=F7xhT_b6l7k

For those that say the temps I'm getting are concerning, I appreciate your feedback. But, what are you basing those concerns on? Do you have specific documentation on modern, sealed transmissions and ATF that states what temps should be of concern and what normal temps should be? Have you spoken with an engineer or someone who specializes in modern transmissions that has shared information related to what temp our transmissions should be operating at and what temps should be of concern? I'm not trying to be difficult, just trying to get some solid facts on the table.

Thanks again for the feedback!

 

[FrenchToasty]

.. people over maintain these things like crazy...

Yourself included, it's not a bad thing.

With the sc your running, won't the extra power cause more strain and stress on the tranny? I know you've been collecting a lot of data, have you noticed any changes related to the tranny?

 

[4RunnerAquasport]

No towing here but I have a good bit of armor. 6000 lbs gvw before camping gear is loaded. Tranny temps (Torque pro app) in Florida get hot, so I installed a B&M cooler and actually put a 5" fan to pull air
thru it for stop and go traffic. Overkill? Maybe but when I get in thick sand, temps go up as well so I wanted to be able cool it down as much as possible. Cheap insurance in the long run imho.

 

[meltdown]

You need to learn to shift if properly (manually) to keep the heat down.

The converter being open will heat it up dramatically. Hold lower gears and you will get much lower temps with the TC locked.

This. Sounds like you're towing with the transmission in D. When I tow, I use 4S and my temps stay easily below 200. Generally, in the 170-180 range. If I switch to 5S or D, the temps will climb to 200 and above very quickly, especially on hills. You'll lose a little more MPG but, it's not a huge difference.

You could probably use D on flat ground if your speeds are reasonable. My typical load catches a lot of wind and when I get to 65mph or above, the transmission struggles to stay locked up.

 

[volpe30]

This. Sounds like you're towing with the transmission in D. When I tow, I use 4S and my temps stay easily below 200. Generally, in the 170-180 range. If I switch to 5S or D, the temps will climb to 200 and above very quickly, especially on hills. You'll lose a little more MPG but, it's not a huge difference.

You could probably use D on flat ground if your speeds are reasonable. My typical load catches a lot of wind and when I get to 65mph or above, the transmission struggles to stay locked up.

I always have it in 4S when I tow on the road. On dirt, on more technical terrain and when going up steep grades, I’ll downshift manually and switch to 4 low as needed. So I’m hitting those temps under those circumstances.

One thing I realized today in researching scan gauge x codes is I’m pretty certain the reading I’ve been getting is at the torque converter. I put in a different code that is supposed to be the pan, or somewhere else in the system. I’m interested to see if that makes a difference on my readings. But either way, the trans oil is still hitting those numbers.


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[jpachard]

Thanks for the feedback.

For those that say the temps I'm getting are concerning, I appreciate your feedback. But, what are you basing those concerns on? Do you have specific documentation on modern, sealed transmissions and ATF that states what temps should be of concern and what normal temps should be? Have you spoken with an engineer or someone who specializes in modern transmissions that has shared information related to what temp our transmissions should be operating at and what temps should be of concern? I'm not trying to be difficult, just trying to get some solid facts on the table.

Thanks again for the feedback!

This^^. Given that new lubricants are really good these days, I’m all for seeing some updated pm schedules too. My Toyota dealer told me the same as far as not changing it etc.


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[ScoMey]

Thanks for the feedback. I have a friend that is a tech/mechanic that used to work for Toyota and is now at Honda, and another friend who is a tech/mechanic at a Lexus dealer. Your take on it pretty much lines up with theirs. They keep telling me to stop worrying about it and to only be concerned if the temps get and stay above 250. I also found the below video this morning which basically says "normal" transmission temp is 10-20 degrees above engine temp. My scan gauge has my engine temp consistently between 185-190. So 200-210 would be "normal" for transmission temp. Further, the guy states that you only need to be concerned that there is a problem when the transmission temp gets to 250-300 degrees or warmer. That video is here: https://www.youtube.com/watch?v=F7xhT_b6l7k

For those that say the temps I'm getting are concerning, I appreciate your feedback. But, what are you basing those concerns on? Do you have specific documentation on modern, sealed transmissions and ATF that states what temps should be of concern and what normal temps should be? Have you spoken with an engineer or someone who specializes in modern transmissions that has shared information related to what temp our transmissions should be operating at and what temps should be of concern? I'm not trying to be difficult, just trying to get some solid facts on the table.

Thanks again for the feedback!

Here's something else to think about... these forum pages are not littered with tales of transmission failures. I do light-to-medium duty towing with my 4R on a pretty regular basis... and stopped worrying about the transmission a long time ago. Don't overload your vehicle, and tow in 4th gear when it's appropriate. I'm not saying the transmissions in our 4R's are indestructible, nor am I suggesting you don't need to add a cooler if you feel it's necessary... just sayin' the tranny's in these things are pretty rugged, and it's not likely you'll experience a failure given the track record of our vehicles. Good luck.

 

[volpe30]

Here's something else to think about... these forum pages are not littered with tales of transmission failures. I do light-to-medium duty towing with my 4R on a pretty regular basis... and stopped worrying about the transmission a long time ago. Don't overload your vehicle, and tow in 4th gear when it's appropriate. I'm not saying the transmissions in our 4R's are indestructible, nor am I suggesting you don't need to add a cooler if you feel it's necessary... just sayin' the tranny's in these things are pretty rugged, and it's not likely you'll experience a failure given the track record of our vehicles. Good luck.

Good points. One of the good things about the current generation being around for as long as it has is a proven track record.

I’m planning on doing some upgrades over the winter, but I’m keeping weight in mind, and a desire to not add too much more given I tow the trailer regularly. The heaviest thing I’ll be adding is sliders, followed by roof rack and aluminum skid plates. That shouldn’t be too bad. Also sticking with C rated stock size KO2’s with weight in mind. I am, and will remain, very hesitant to add front and rear bumpers, a winch, etc., due to vehicle weight plus trailer.

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[Rmack]

If mine were reaching those temps I would definitely do a fluid / filter change. One reason is that the fluid will break down over time, especially at elevated temps. Then it will not have the same properties to protect from heat / friction.

Another reason is that there have been a few members on here who found their transmissions underserviced from the factory.

I changed mine at 20k. I do not do any severe driving, but have worked on hot rods all my life and rebuilt a few transmissions. You can tell when one has been serviced regularly, and the cost is nothing compared to the vehicle or a new transmission. The initial change removes a lot of break-in debris from the clutches.

At a minimum it will be a piece of mind for a small cost.

BTW, very nice set up you have there!

 

[wfo9]

If mine were reaching those temps I would definitely do a fluid / filter change. One reason is that the fluid will break down over time, especially at elevated temps. Then it will not have the same properties to protect from heat / friction.

Another reason is that there have been a few members on here who found there transmissions underserviced from the factory.

I changed mine at 20k. I do not do any severe driving, but have worked on hot rods all my life and rebuilt a few transmissions. You can tell when one has been serviced regularly, and the cost is nothing compared to the vehicle or a new transmission. The initial change removes a lot of break-in debris from the clutches.

At a minimum it will be a piece of mind for a small cost.

BTW, very nice set up you have there!

You should not use an old school mindset to maintain a modern vehicle. What's next.. change your plugs and points every 20k?

 

[e60ral]

i bet you also believe that lifetime fluids never need to be changed