PSA: Check Your Trans Fluid Level

[StormRnr]

TL;DR If you hate the Tacoma transmission, it might be under-filled.

I have a 2017 TRDOR with the 6-speed Auto 100k Miles, 2" lift 285/70 R17 tires.

It has always had the common transmission issues of downshifting early and holding the lower gear FOR EVER going up hills. Hunting for gears. NEVER using 6th. Slow response. Weird behavior of the torque converter lockup. I know that "The Tune" is supposed to fix it, but I've never wanted to mess with that.

Two weeks ago I did a drain and fill on the transmission per this video:

Source: https://www.youtube.com/watch?v=rNqYpEpmUng


I drained out 2 QT.

I put back 3.5 QT and when I did the temp check and level drain I barely got any out. So the trans was 1.5 QT low. I've read on forums and such that that is common. Even on newer trucks with fewer miles.

After this I had to do a road trip from Reno, NV to Stockton, Bakersfield and back via 395 through Bishop and Mammoth. Lots of hills, flats, turns, a reall variety of driving conditions.

The transmission is now "normal." Not as great as our 10 speed ford transit, but WAY WAY better than the tacoma has been for the last 4 years I've had it.

It holds 4th gear longer going up hills. Over I80 from Reno to sac it never used 3rd.

It uses 6th a lot on flats. From Sac to Bakersfield it was in 6th most of the time and got 20 MPG for the leg from Reno to Modesto.

I drove up through the Kern River canton to Lake Isabella and used "sport mode" and "ECT." Shifting was faster, firmer and more responsive. It holds RPM higher and has faster available power.

On 395 there are a number of passes that usually give me trouble. Bishop to Tom's Place. This is 10+ miles of continuous steep grade. Truck held at 70mph in 4th gear.

Deadman Summit: Short but steep. The truck went into 3rd, but shifted out as soon as the grade backed off before the top. Previously it would hold 3rd until well after the top.

Conway Summit: STEEP pass out of Mono Lake. Went into it at 70 MPH in 4th gear. It shifted down nearly halfway, then shifted back to forth until I had to slow down for traffic. It has NEVER done that on that hill. It's always been third the whole way.

The mileage for the trip was about 18MPG. No gear hunting, no holding lower gears for way too long. Better engagement all around. The torque converter lockup seems more effective and positive than it did before.

I recommend doing the drain and flush if you hate the behavior of the Tacoma transmission. I see no need for a tune now.

-M

 

[Mike Z]

What do you consider a drain and flush? I know on a modern auto transmission the torque converter has no dram plug or access. I've had people tell me they disconnect a trans cooler line and run it into a drain pan while adding fluid to the fill. What I did on my 04 Camry was to have the fluid changed with the pan dropped so they could change the screen cartridge and then a few hundred miles later I did a drain and fill myself. I think that gave me about 75% new fluid.

 

[StormRnr]

What do you consider a drain and flush? I know on a modern auto transmission the torque converter has no dram plug or access. I've had people tell me they disconnect a trans cooler line and run it into a drain pan while adding fluid to the fill. What I did on my 04 Camry was to have the fluid changed with the pan dropped so they could change the screen cartridge and then a few hundred miles later I did a drain and fill myself. I think that gave me about 75% new fluid.

Just drain from the transmission.

I didn’t go deeper than that yet, though I’d consider a more regular regime of that. Once a year maybe.

 

[MikeB]

From everything I have read and viewed, I am of the understanding that a "flush" and complete replacement of transmission fluid is not a good idea. A simple drain and refill is what is usually recommended.

The Car Care Nut on You Tube recommends that you do not overdo the transmission fluid changes. Take a look at this Short:

Source: https://www.youtube.com/shorts/MiS248FXIs8

 

[Mike Z]

The Car Care Nut recommends changing the fluid every 60,000 miles or if you've never done it and the engine has over 100,000 - 120,000 leave it be and don't change. The reasoning is the a higher mileage engine with the original fluid has worn clutches and the dirt particles are helping it grab. A total change might make it start slipping.

 

[StormRnr]

The Car Care Nut recommends changing the fluid every 60,000 miles or if you've never done it and the engine has over 100,000 - 120,000 leave it be and don't change. The reasoning is the a higher mileage engine with the original fluid has worn clutches and the dirt particles are helping it grab. A total change might make it start slipping.

TBH I'm dubious about most of the things that guys says. He may be right, but maybe not. For me he doesn't exude credibility just because he has a lot of long videos with tons of views.

Either way, my truck has 100k and benefited from the drain and fill.

-M

 

[Mike Z]

I personally will drain and fill at a local family transmission shop just before 60k or when the warranty will be up and have them drop the pan for inspection. Many of these truck were delivered underfilled possible because some of them had the coolers installed at the port instead of the factory. The PDI that is done when new does not give the dealer enough time to check the level.

One thing TCCN had said that I don't agree with is that the driveline vibration when slowing from about 25-30 mph to 13 is caused by the truck being body on frame instead of unibody. That is nonsense because the last generation Tacoma did not do this nor does the Frontier or Ranger. Mine does this slightly but not bad enough to risk something else being messed up performing the TSB.

 

[StormRnr]

Shops also only see the failures. So TCCN might say what he says about not changing fluid because he's seen the failures correlated to it. But he doesn't see instances where there are no failures, and has no idea how many of those there might be. He could be seeing 1% or 99% and there's no way to know.

 

[Mike Z]

It make sense to change it regularly or not at all if it's high mileage and been neglected. Same thing for brake flushes. If you've only been adding brake fluid as needed and then a shop recommends doing a brake fluid flush and you have 150k doing it might cause brake cylinder or caliper failure from pushing the sediment at the bottom of the master cylinder through the system. Many dealers have the displays with the test tubes with dirty and clean brake, power steering and trans fluids.

 

[MikeB]

All in all I have a tendency to believe most of what an ASE certified mechanic has to say. By the same token I am less likely to believe what an internet forum poster has to say.

 

[Tomahawk Dog]

I tend to believe that if an owner neglected their vehicle, that thinking taking care of it now will make things just fine.
Sort of like beating your pet dog and later in life asking for friendship and devotion, ....... not gonna happen!

People are just that way,...
Save a few dollars today by changing your oil every 10,000 miles because they want or feel that they fall into that bracket.
When in reality 90% of people fall into the 5,000-mile bracket.
3 years later,......... they bitch because they have an issue.

Engine - transmission - transfer or gear oil ALL the same,.....
I am done,.... thanks for reading.

 

[Mike Z]

One thing I just noticed in the video for post #1 was that the thermostat in front of the line to the cooler was not pinned. I was told the thermostat must be held open or you might not get a true reading after draining, Also what is the correct place to check for the vehicle being level? I would assume the pavement in the area the tires will be but I also have seen people put a level on the bottom of the pan

 

[MikeB]

I have not checked my Tacoma yet but from what I have seen in the videos, only the Tundra, Sequoia and LX570 with the external transmission cooler have that thermostat that needs to be depressed and pinned for an accurate fluid level check.