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89 Posts
Drain/ Fill exact amount that you drain, replace with new. Just make sure the Fill Plug can be loosened first. With Emergency Brake & Foot Brake depressed, slowly shift thru all gears twice. Let it sit a couple hours.
Don't start with hot Tranny as this fluid volume expands a bit at full running temp.
After 2nd D/F you will be good for at least another 30-40K miles.
As long as You have owned since Brand New and know NOBODY ELSE has touched YOUR Tranny, you can rest assured the Original Factory Fill is at correct level.
No need to drop pan or replace filter at this exchange. Maybe second, definitely 3rd since you tow.
Smart move on your part to start doing service using OEM WS this early.
And as you do tow, make sure to also change Engine Oil (Full Synthetic) and Filter every 5K or earlier.
And take a peak/sniff of Radiator Fluid while you're in there, as well as rest of levels. I would recommend replacing both difs and Transfer Case oils as well for safest operation and longevity. And Grease All U Joints/Spider Zircs on Drive Shaft!
When servicing brakes, do flush a few ounces thru each Caliper, as that's where the most heat/wear occurs, again especially because you tow.

She should run forever!
Especially if the Stealership never touches it and you DIY.

89 Posts
So, the Tundra has a sealed transmission. That means that the fluid is not allowed to freely interact with air. The oxygen in air degrades the fluid over time and it has been known since the 1950's that if you seal transmission fluid from air, it is not degraded by the oxygen. The air that is in the transmission when assembled does interact with the fluid until the oxygen is used up and you are left with an inert atmosphere of nitrogen that protects the fluid.

In a sealed transmission, if you don't tow heavy, off road your truck, and drive in such a way that you minimize shifts and keep the torque converter locked up, your transmission fluid will last a lifetime, which probably means several hundred thousands of miles.

However, if you tow heavy, drive your truck so it is constantly shifting or the torque converter is running unlocked a lot (ie, around town driving, off-roading, etc.), the fluid is being stressed through the torque converter and will wear over time and need to be replaced. In these situations, you will need to replace your fluid.

It is normal for transmission fluid to turn maroon in color. But when it turns brown or black, that is bad. The brown/black is caused by the transmission fluid getting burnt from heat and stress and indicates that you definitely need to have the fluid changed and may have done damage to your transmission.

Personally, I only occasionally tow a light travel trailer and when I do, I keep the torque converter locked up and drive it easy. When I am not towing, I basically and driving long distance on highways with little to no stress on the transmission. In my case, I think a drop the pan, replace the filter and fluid in the pan, at about 100-150K interval is sufficient for my transmission fluid to last several hundred thousand miles (and that is what I have done so far and am at 180K and no issues).

But if you are in town driving, towing heavy and hard, off-roading, etc, you should change your fluid more often and consider a full fluid change instead of just replacing what is in the pan.

Last, you won't hurt anything by changing the fluid more often than needed. It just costs money. But you can damage a sealed transmission if you don't change it right and don't get the level right, so make sure you know what you are doing or that your mechanic knows what they are doing. It is not an easy process. I had mine done at the dealership and the filter/pan fluid change was under $200. I am sure a full fluid change is probably double that price.

$200 is very inexpensive sounding for a fairly Labor intensive pan drop/filter/5 qt WS fluid service.
You sure they did the job???

89 Posts
I would just like to see one link to any of these claims of Toyo Truck Trans Sealed relevance by Manufacturer, ie Aisin.
Motor Oil is MUCH more Hygroscopic than Tranny Fluid and last much much longer by just that fact.
Tundras 2004 & earlier with Tranny Fluid Dipstick are what is considered an example of Nonsealed Automatic Transmissions, correct?
Bunches of those still run ing great well past 250K having had no Fluid Exchanges, I do believe.
Tossing equations is all well & fine Professor, but a source verifying theorems and calculations specific to an actual effect affecting WS OEM or earlier requirements fluids would certainly settle the case better.
Until then, making popcorn!

89 Posts
OK. For those who want to learn, here we go.

Here is a link to the patent for a sealed transmission breather. This will explain why a sealed transmission has a breather and how it prevents or minimizes oxidation of the transmission fluid. US5129422A - Transmission breather control valve - Google Patents

Here is one from the society of automotive engineers (SAE) also about breathers on sealed transmissions, and although you have to pay to read this one, you can read the summary and get the idea of what they are talking about. Transmission Air Breathing Suppressor (TABS) Valve - A Device for Improving Automatic Transmission Fluid Life

Here are a series of 5 history of transmission fluid videos done by Prof John Kelly who is the most knowledgeable transmission nerd I know of. In part 4 of the history of Chrysler Trans Fluid he talks about the discovery of sealed transmission fluid longevity and explains why preventing people from checking the fluid and adding fluid and exposure to oxygen are all bad and led manufactures to eliminate anyone being able to check or change fluid easily. He talks about doing a lifetime fluid video, but it does not look like he every finished it. If anyone can find it, drop a link because I would love to watch that.

This is a good article that has a section that talks about lifetime fluids. It has a good history of transmission fluid and talks about the original discovery of hermetically sealing fluid in the transmission by Chrysler .

A couple more things:

I don't care one way or the other if you change your transmission fluid. I can only explain the engineering behind why manufactures are saying that under normal driving conditions you don't have to do that. You do what makes you feel good.

I am not going to explain the math. It's Jr high school level chemistry and algebra.


For those who want to argue against Toyota's recommendation to not change the trans fluid, I ask what is Toyota's motivation? Are they trying to boost their 15 year/300,000 miles transmission sales? Why would they want to sell less transmission fluid and why would the dealers want to do less maintenance work? And why would they want to purposefully shorten the life expectancy of their trucks over transmission fluid?

I think the answer is that they think their transmissions on average will last 3-400K miles without any service, and even when the transmissions does fail, it will probably not be because of the fluid. And that happens to be my definition of lifetime as well, so I don't plan to do anything more than a pan drop and filter change every 125-150K.

The best of the best to ya all!

Thank you!
Exactly and understandable for my addled brain, and like you, We can only share, not any stake in anybody else's choices, trucks or business.
Carry on, my Tundra Fam.
Keep On Truckin

89 Posts
I really wish it was a filter.
It is really an ultrafine screen though!
As with most of my maintenance and rebuild items, I purchased mine from Toyota long ago.
Didn't see the Pando and Disability on the betting form, so have really reduced the use of my Girl greatly.
But when the time comes I'm stocked up!

After watching that YT on Toyota fluids, I am now afraid to use the 2 gallons of Valvoline WS Compatible to do my upcoming D/F.
No issues caused using it posted/stated by others.
And it's what I have. Guess I'll risk on one D/F and full replace if any new strangeness occurs.
Can't go wrong using Toyota WS like my 1st D/Fs using over Gallon and a half.

The next batch of Popcorn is in the microwave now!
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