Transmission service question (1 Viewer)

[tominboise]

My 200 has 130k miles on it and I last serviced the transmission at 90k, with a drain and refill (draining the pan and also pumping out through the cooler lines). I used 12 quarts of Toyota WS fluid. I need to change it again - should I drop the pan and replace the filter this time around? Or are most people just draining and refilling?

 

[AZLX570]

You're doing it every 30K?

 

[TLC2013]

Every 30k-40k is more than often enough for a pan and refill service. Should take about 4 quarts to do the pan fluid swap.
This is my current plan for tranny services. At 100k I did a full 14 quart exchange, old fluid looked dark and used. Switched to Amsoil SS ATF at the 100,000 mile fluid exchange.
At 130k I did a drain and fill of the pan ( about 4 quarts) and the Amsoil ATF looked just about brand new. Nice and cherry red. I’ll continue with the 30k pan drain and fills as long as the fluid still continues to look good and may even go to 50,000 service internals.

 

[Malleus]

Your transmission doesn't have a filter, it has a screen.

Keep doing what you're doing and you'll be fine. Replacing transmission fluid regularly is the best way to ensure longevity. The recommended intervals for different driving conditions are in the Owner's Manual Supplement, Maintenance Schedule.

Draining only the pan is a waste of money; you're only mixing good oil with bad. You cannot "refresh" contaminated oil. You can check teh fluid condition by inspecting the overflow plug. You used to be able to check the dipstick, but some accountant decided that part was unnecessary.

 

[TLC2013]

This is after 30,000 miles on the Amsoil SS ATF. Looks like I am dumping nearly brand new fluid.

 

[tominboise]

You're doing it every 30K?

40k on this fill. I have no idea what the PO did - I bought it with 70k on it.

 

[tominboise]

Your transmission doesn't have a filter, it has a screen.

Keep doing what you're doing and you'll be fine. Replacing transmission fluid regularly is the best way to ensure longevity. The recommended intervals for different driving conditions are in the Owner's Manual Supplement, Maintenance Schedule.

Draining only the pan is a waste of money; you'r eonly mixing good oil with bad. You cannot "refresh" contaminated oil. You can check teh fluid condition by inspecting the overflow plug. You used to be able to check the dipstick, but some accountant decided that part was unnecessary.

So don't worry about dropping the pan itself and changing the screen? Just drain and fill? Note that I will flush all 12 quarts out, through the cooler lines.

 

[Malleus]

Running new fluid through it will flush the screen for you. If you can run it until it's hot the day before and drain it overnight. That'll make the flush process quicker.

 

[TLC2013]

At my 100k tranny service I dropped the pan and changed the screen / filter. Won't be doing that again. While I was able to get all the pan bolts out easily, no issues there, the pan itself was fused to the gasket and transmission. After separating everything and cleaning up the mating surfaces that filter/screen was clean, no gunk or metal in it after 100,000 miles.
It did give me peace of mind to have the new screen/filter and knowing that things were hunky-dory inside the tranny almost made it worth the hassle.

 

[jlm43]

My 200 has 130k miles on it and I last serviced the transmission at 90k, with a drain and refill (draining the pan and also pumping out through the cooler lines). I used 12 quarts of Toyota WS fluid. I need to change it again - should I drop the pan and replace the filter this time around? Or are most people just draining and refilling?

I'd probably drain the fluid and see how it looks. If it's clean, stick with a simple drain and fill of the pan. If it's dark after 40k miles, it might be a good idea to drop the pan, change the screen, and give everything a good cleaning.

Running new fluid through it will flush the screen for you.

Where do the contaminants go when it's done this way? I get that the new fluid can break up some of the sludge and a few drain and fills could clean most of that up, but I'd like to think that the screen will keep any damage causing junk within it's media until it's replaced.

 

[Malleus]

Have you ever seen the screen? It's just a screen. There is no media; it's not a filter. The valve body "filters" are screens too.

No number of drains and fills is going to clean the pan. You have to remove it to do that. If you regularly replace the fluid, there wil lbe no sludge buildup, and therefoe no reason to remove the pan.

 

[jlm43]

@Malleus that makes sense. No, I haven't seen one of the screens in person.

I've been contemplating what to do with my new to me LX (2013 with 93k miles). I'm on the schedule at the local Toyota dealership to have a full fluid exchange done with dropping the pan and replacing the screens. After this initial baselining, I think I'll just plan on doing the basic & drain and fill to keep it somewhat fresh and prevent any major buildup.

I've heard many say that you shouldn't do a full fluid exchange on higher mileage vehicles but I don't really get behind that comment. I'm still learning though. I had the full fluid exchange and screen replacement done on my 100 when it had 230k miles on it. Shifting was never bad but it was super smooth after and the average running temps dropped to the 135 range.

 

[bloc]

Draining only the pan is a waste of money; you'r eonly mixing good oil with bad.

Not if you do it often enough.

 

[mark71]

Curious if anyone on here has had a transmission failure?

 

[Malleus]

It's more of a waste of money the more often you do it. You cannot clean contaminated oil by mixing it with clean oil. All you do is contaminate more oil.

 

[Malleus]

@Malleus that makes sense. No, I haven't seen one of the screens in person.

I've been contemplating what to do with my new to me LX (2013 with 93k miles). I'm on the schedule at the local Toyota dealership to have a full fluid exchange done with dropping the pan and replacing the screens. After this initial baselining, I think I'll just plan on doing the basic & drain and fill to keep it somewhat fresh and prevent any major buildup.

I've heard many say that you shouldn't do a full fluid exchange on higher mileage vehicles but I don't really get behind that comment. I'm still learning though. I had the full fluid exchange and screen replacement done on my 100 when it had 230k miles on it. Shifting was never bad but it was super smooth after and the average running temps dropped to the 135 range.

The dealerships make money selling parts. Replacing the screen won't hurt the tranmission, but it will drain your wallet.

The old wive's tale about not changing ATF is flawed; there are three primary components in an automatic transmission:
1) the clutches and steels - there are several for each gear, unlike a manual transmission which has only one clutch plate and one pressure plate and which are used to change from any given gear to any other;
2) the valve spools in the valve body, which are close fits in the bores they operate in; and
3) the fluid pump, which is a gerotor comprised of one external pump gear and one internal pump gear, in which the external gear turns.

The pump moves fluid into the valve body, where it is in turn moved into a section of the transmission containing the desired gear and applied to the pressure side of a piston, which in turn clamps the rotating clutch discs against the nonrotating steels (the steels don't rotate, but they can move along the long axis of the tranmission, as do the clutches).

The valve spools and pump rotors (gears) are close fits; any debris that gets between them and the mating surfaces they contact impedes their motion and potentially wears them or causes them to fail to move smoothly. The debris always comes from the clutch plate friction material that falls off when the clutch plates are squeezed against the steels, but haven't yet been clamped tightly enough to casue them to stop turning. This is what you want to remove by changing the ATF. If you leave that in long enough and other parts, usually the steels, start to wear and add to the contaminants in the fluid.

Failure to change the ATF, and subsequently remove the clutch frction material, causes improper operation of the shift or oil flow components; cluch wear causes slippage. This is why transmissions fail, typically (there are also failures due to component failure, but these are rare in Land Cruisers).

The clutch "packs" operate exactly the same way manual clutches do, except they are in an oil bath to keep them cool and to cause the system to operate (the transmission pump provides fluid for the valve body to use to shift the gears, in much the same way a clutch pedal does in a manual transmission).

This is why keeping the fluid clean is important, and why exchanging it for clean fluid when it gets dirty (contaminated) cannot in any way degrade the operation.

As to "changing" fluid by simply draining the pan, try this thought experiment: you are given the job of cleaning a dirty pool. Instread of draining the entire pool, you decide to use a bucket to remove water from one end, and, after emptying the bucket and refilling it with clean water, you pour it into the pool at the other end. How well do you think that'll work? That's exactly what you're doing when you replace only a portion of the ATF by draining the pan and refilling it.

 

[bloc]

It's interesting you tried to visualize things with a pool analogy.. that applies even better to a specific part in our transmission.

A fluid exchange doesn't drain the torque converter, it just flows fresh fluid from the pan into it at a pretty low rate, where it is mixed *thoroughly* (this is the very definition of turbulent flow) with the old fluid already in there, slowly diluting it until most of what's in there is clean.

This would be like pumping fresh water into a violently swirling swimming pool and expecting only the dirty water to flow over.

Plus, the fluid volume trapped behind the pistons in the drums, which there is no real way to exchange without activating each clutch multiple times. I'm sure there are more places.

You could also, in theory, do a very high number of drain & fills, with each diluting the old fluid progressively more, resulting in 99.9% clean, new fluid inside the transmission.

Not that anyone does that.

My point is to say drain & fills, done often enough, result in enough of the fluid within the transmission being fresh, and enough contaminants removed, that ongoing drain & fills is a decent option for people that don't have the resources for a fluid exchange.

Though all else being equal I'd usually recommend a fluid exchange.. primarily because it wastes a lot less fluid.


To be clear, a single drain & fill on a 93k mile vehicle is pretty much pointless, unless you repeat it 4 or 5 times relatively soon.

 

[jlm43]

@Malleus @bloc thanks to both of you for the explanations. I didn’t fully grasp the inner workings of the transmission but I’m getting there. I’ve spent the last twenty five years wrenching on turbine powered helicopters so while my mechanical skills are on point, a car transmission is something I’ve never dug into.

I’ll move forward with the initial plan of doing the full fluid exchange / pan drop / screen replacement. When I called the dealership they didn’t want to work on a Lexus so I dropped by and talked with the service manager. We’ve had some conversations before so the past relationship helped and he was fine with bringing it in. Hopefully everything goes as planned.

 

[tominboise]

There is a technique, which I did the first go around, where you drain and refill the pan, pin the thermostat open and disconnect one of the cooler lines, and start the rig. Pump out 4 quarts of fluid and shut the car off. Pump in 4 fresh quarts. Start up again and pump out 4 more quarts. Shut it off, reconnect the cooler line, pump in 4 quarts of fresh fluid and then go through the fluid level checking procedure. This gets most all of the old fluid out.

 

[bloc]

There is a technique, which I did the first go around, where you drain and refill the pan, pin the thermostat open and disconnect one of the cooler lines, and start the rig. Pump out 4 quarts of fluid and shut the car off. Pump in 4 fresh quarts. Start up again and pump out 4 more quarts. Shut it off, reconnect the cooler line, pump in 4 quarts of fresh fluid and then go through the fluid level checking procedure. This gets most all of the old fluid out.

Yep, that’s the at-home version of the Fluid Exchange we are referring to. Works great.