Paranoid - Did my mechanic fill my ATF correctly?

I use a local Lexus/Toyota only specialist mechanic and at 105k miles he recommended a transmission drain and fill along with coolant.

I may be over analyzing every shift but it seems a tiny bit different? I’m not sure if now I’m just trying to pay attention to shifts and what was normal I’m now feeling as different even though it was how it always acted.

He said they drain and fill about 4qts. Seems like there is a big process with jumping things and pinning things. How can I be sure they did it correctly without the Toyota tools (or maybe they have them?) What questions can I call back and ask to make sure it was done the right way? What can I look for to make sure it wasn’t under or overfilled? Will I get a warning light?

 

4 quarts is about right.

I drain 4 and add 4+ a pint. I only did the transmission temp procedure the 1st time.

100*-115* is not going to be a huge difference than 70* in fluid volume.

I do regular heavy towing.

Changing the fluid is much more important than having the fluid a 1/4" above or below the correct level.

 

At 105k, I wouldn't be surprised if it shifted a bit better after a fluid change. Know real way to know if he did it correctly. Would need to add another quart and follow the process for draining excess at the correct temp.

 

It’s smooth but I feel like the shift points and logic is a bit weird

 

The drain and fill process and doing the temp check is actually very easy to do without any jumping wires in the OBD or Toyota TechStream. All you need is an OBD device that can read the ATF pan temp and you open the check bolt between 99°-111°F. If no fluid comes out then you need to add some and redo the check process. If fluid does come out then you have enough in there and you want to let it slow to a trickle, basically when the flow is not strong enough to go straight down and starts to go down the side. Then put the check bolt back in and you are good to go. The check process is done while the engine is running. If you wanted to make sure they did it correctly you could add a half a quart and do the check process over.

 

Thanks - a lot of posts have me think 1oz of extra fluid will grenade the trans. Is there any room for error?

 

What I take from this is a specialty Toyota mechanic probably knows how to do this properly without special Toyota scan tools?

 

There's a number of ways to do the check without proper tools. And frankly checking the level without doing anything special I would bet is totally fine. I wouldn't sweat it. Any changes are most likely from fresh fluid.

 

The pan can accommodate up to an extra quart of atf. That's how I've been running it for a few years. I go by the change in flow from steady to slight stream.

 

If the guy recommended you have a drain and fill done, I'd have to assume that he knows how to do it properly.

 

I believe the proper way to do it - and these could be questions to ask the mechanic/shop:
- frame level (thought its debated on how much difference this really makes)
- overfill trans a bit - (1/2 qt-ish). If 4qts drain out, I'll put 4.5qts back in
- pin trans thermostat OPEN if you have a trans cooler
- bring trans up to temp (needs to be 99*-111*) - monitoring with ODBII device - ATF temp 1 is the pan
- once trans/ATF reaches 99* - and remove trans pan check plug
- wait until drain from the check plug slows to a steady trickle and replace plug

At least this is how I've done it that past couple of times I've done my own ATF drain/fills.

 

Any reason you overfill it?

 

This is expected and normal, unless you do drain&fill every year. Old fluid degrades, pressures deviate, friction modifiers consumed, TCM keeps adapting to ever changing conditions. Replace the fluid and its properties changed drastically from what TCM used to see just one engine start ago.

It will learn it, don't worry.

 

Interesting. I didn’t realize it would have to relearn every time. But still better off doing it and letting it learn? Or should I do it more often now?

 

I saw a presentation by Aisin, they recommend replacing fluid in their transmissions every 30k km. Km, not miles.

 

That’s like 18k miles??

 

Yeah. That's for their sealed smaller units, and still seems to be over the roof. But I was laughing at this, yes. Transmission manufacturers says: "replace ATF every 20k miles", car manufacturers says: "ATF is lifetime". Same unit.

I do drain&fill about every 20k miles, which is couple of years.

 

I do a drain and fill every 15-20k, no need to ever fully replace the fluid that way. Oh and never bother to replace the filter, I've done it and opened it. Not worth the hassle plus the pan bolts snap easily.

 

You are way over thinking this.
A drain and fill is super easy. No need to pin or jump anything. All that does is tell you on the dash when the trans temp is in range to pull the check plug.

No need to do that if you have even the cheapest of scan tools, which I am sure your mechanic has a pretty good one.
If he is a Lexus/Toyota specific he pretty much is going to have TechStream.

He also likely reset the ECU and the transmission has to relearn to your driving.

 

There are pans available for added capacity and cooling but it does not address the strainer/filter pickup still being at its original height.
I've seen adding a little extra fluid alliviate p2757/2714 codes, a little cooling but mostly keeps the strainer pickup submerged to the filter housing. Too much beyond this can cause issues. When having codes or shifting problems adding atf and checking solenoids is the easiest that you can do. Nothing will solve a fried clutches etc.
Most of us will benefit with a standard drain/fill every 2 years. Keep the transmission cool!

 

But of course! The tolerance is +/- 7 pico-liters.

 

I'LL have to say I was slightly concerned when I had my 213000 mile 07 CM tranny drained ad filled last year. Immediately following the service the truck shifted strangely from gear to gear. Everything worked as it should but there was a very noticeable difference when it did shift it was like it was really different from before. Its hard to describe other than shifting became really distinct between each gear. I figured I wouldn't panic right away so after maybe 2 days, the truck reverted to shifting as it was before......like butter. I haven't had any problems and I'm now at 250k+. Don't stress give it a few days and see how it goes. I'm no mechanic but I'm guessing you will be alright.

 

sort of where I am at. Today it seemed to “gear hunt” where it wanted to upshift then immediately downshift. Couldn’t replicate it. Just a weird blip. Wish I wouldn’t have had it done honestly. Not worth this stress.

 

Will the truck get to that temp without pinning the thermostat? Can I do a check after a quick drive or something?

 

It's gets to that temp very quickly, I wouldn't suggest driving or it will go over that temp pretty fast. You need to pin the thermostat open in order to to a proper level check because the thermostat doesn't open until around 180° and the radiator fills with fluid, if the thermostat is closed all the fluid is in the pan so if you checked it with the thermostat closed you would drain out too much fluid from the check bolt. Pinning the thermostat is extremely easy you just push in the button and use a pin that fits through the hole, I use the one that came with the thermostat when I purchased my cooler but I'm sure a paper clip would work.

 

so I’m still confused - what’s the actual science behind the fact that if 4 quarts is removed and measured, you can’t simply add 4 quarts of new fluid?

 

You certainly can do that if you don't have any transmission leak and the previous service was properly filled.

 

So why the whole hubbub about pinning the thermostat and jumping the obd yada yada yada? If mine was factory filled and this was the first change, 4 in 4 out, shouldn’t that be okay?

 

Assuming fluids are same temps and nothing gets spilled - yes. I did my first two this way - then by the third decided I better verify level and did the pin and pull check plug at temp verification.

 

If you have a truck without trans cooler up by the radiator (I think 2018- 2021 does not), you do not have to worry about pinning the thermostat. The procedure you mentioned is when you do not want to drain and measure.