05 Cadillac STS (5L50) transmission fluid & filter change

[kevm14]

TL;DR: this was not that bad.

First, I had to lift the car up in the air and get it fairly level for filling.

WP_20170531_10_52_01_Pro.jpg

Before I drained a drop of fluid, I made sure I could loosen the fill plug in the trans case. By the way, the internet said the drain plug would be a T-47 and the fill would be a T-45. Both plugs that came with the new filter were T-45. And so were the ones on the car. Ok that's fine.

I was able to just barely jam my 3/8" ratchet with T-45 into place. I had to squish the heat shielding but I just got it to fit. It loosened without too much effort.

With that done, I removed the drain plug and witnessed the glory of the transmission pan drain plug. When that was done, I put it back finger tight and buzzed all the 10mm pan bolts off with my Ryobi impact, like I did with the truck. Makes that super easy. I did have to use a universal on one bolt and a box wrench on another. I took this opportunity to try out my Harbor Freight ratcheting wrenches, which worked great.

Remove the pan. This is what you will see.

WP_20170531_10_51_20_Pro.jpg

Here is the fill plug by the way.

WP_20170531_10_51_41_Pro.jpg

Once the pan was down, I pulled the filter. It is held in place similar to the 700R4/4L60-E with no retainers. To remove the old seal, just a little prying with a flat screwdriver does the trick. Oh, I should probably mention: the old fluid looked like engine oil. It did not smell burnt but didn't smell new, either. Again, it resembled engine oil in color. It was the correct viscosity for transmission fluid. It was due for sure.

Then I cleaned the pan and magnet which didn't have too much on it.

WP_20170531_12_40_06_Pro.jpg

The gasket is the reusable type (metal with an inner perimeter seal) but it looked a little tired to me so I made a trip up to Herb Chambers in Warwick and got a new one for $14.xx. While I was there I picked up some touch up paint which was like $22.50. It has a base and a separate clear coat step so it's pretty fancy. This car doesn't have many chips but I noticed one today on the right front fender.

Once I got the new filter on the pan, I reinstalled the pan and put the new drain plug in it. Now what to do about refilling...

Oh, this pump should work. Wait, it actually not only has the perfect length tube, but even threads on to the trans fluid container?? Hell yeah!

WP_20170531_13_15_59_Pro.jpg

I was able to jam the end into the fill hole. Then I pumped 4 quarts into the transmission and started the engine. The FSM said somewhere in the 85-122F range is correct for filling, which is like filling a differential (fill until it comes out). I used my new IR thermometer on the pan to make sure I was at least in the mid 80s. Then I pumped the 5th quart in. It took some portion of the 6th (and last quart I had) before it was full. Yes, this process is a pain and dangerous as I am laying under hot exhaust while the car idles. Screwing the fill plug back in was interesting but I got it done.

Road test results?

Actually it shifts even smoother than before, not unlike a new transmission. The lockup shudder is still there but maybe not as bad. I did not get on the highway to really test it. I wish I could have flushed all the old crap out of there.

I guess the next step is do another 5 quart change, leaving the new filter in place. That should give me 75%+ new fluid. I could even do it again in another couple of months. But I think with the next change, I will add the Lubegard additive.

EDIT: The FSM says the total fluid capacity is 9.4 quarts. Say I added 5.5. That means I actually changed 58.5% of the fluid. Also this transmission was made in France.

[kevm14]

Now I will post a collection of interesting sections from the FSM.

First, I think this is a repost. It is the torque converter clutch shudder TSB. Came out in Sep 5, 2007 so obviously this happened to fairly new vehicles.

[kevm14]

This article is like informational regarding how the fancy new 5L40 and 5L50 does business. Mainly the article points out that the torque converter locks a lot more often than previous transmissions (somewhat ironic) and it also explains all the different shift algorithms and how they apply to the various vehicles that use these transmissions.

I will highlight two.

Shift Stabilization (CTS, SRX, STS, XLR)
Shift stabilization is used to minimize shift business, or hunting between ranges. Based on several
inputs and a map of engine torque at various RPM and throttle position, the TCM determines before
making an upshift whether the engine will be able to maintain vehicle speed in the next higher
range. If it calculates that it cannot maintain speed, it will prevent the upshift from occurring.

This is part of why the transmission always seems to be in the right gear.

Adapts (CTS, SRX, STS, XLR)
Adapts continually compares actual shift times to desired shift times. The transmission controls
make hydraulic adjustments to assure the actual shift times approach the ideal shift time the next
time the shift is made for similar operating conditions of vehicle RPM, engine load, and road load
conditions. The adaptive shift process continues for the life of the vehicle to provide consistent and
optimized shifts.

This is normal but I think more sophisticated than previous transmissions. On the 4L60E for example, I think the only learned shift was the 1-2. Of course this has a dark byproduct of potentially masking problems until it is so worn out that it can no longer adapt and by then, it is probably all worn out. But it's a transmission - do fluid and filter changes as required. Make sure the fluid isn't becoming contaminated with coolant. Otherwise, there's not much you can do.

I have also attached another article on shift adaptation which specifically explains how to accomplish relearning in all cells so the customer does not complain of odd shift quality while it relearns.

EDIT: Oh yeah this is definitely more sophisticated than the 4L60-E.

The Hydra-Matic 5L40-E/5L50-E uses a line pressure control system which has the ability to adapt the system line pressure in order to compensate for normal wear of clutch fiber plates, seals, springs, etc. The adapt feature is similar in function to fuel control (integrator/block learn).

The Hydra-Matic 5L40-E/5L50-E transmission uses the adapt function for garage shifts, upshifts, and TCC application. The transmission control module (TCM) monitors the input shaft speed in order to determine if the shift is occurring too fast or too slow and adjusts the pressure control solenoid in order to maintain the correct shift feel.

Basically all shifts are learned. It even adapts to TCC apply which is impressive. If only the clutch material itself worked properly...

[kevm14]

This one is interesting. Apparently the trans mount can short to the support. I almost wonder if my STS has this problem. It's not very pronounced and it could easily just be something else.

[kevm14]

The actual fluid/filter change procedure. Even in here they say to replace the drain and fill plugs. I have no idea why. New plugs with O-rings did come with the AC Delco filter (a gasket did not).

Though I am really including this just for Bill.

Important: Fluid pan gaskets are reusable. Replace the gasket ONLY if the sealing surface is damaged.

Right in the FSM. Kinda funny that the metal drain/fill plugs need to be replaced but the gasket is reusable. But there you go.

Also including the actual check/fill procedure which I had to do. I don't know what all this crossmember business is about. I didn't touch it. This step chart makes transmission fluid checking and filling look ridiculously complicated. In reality, it is a little tedious with the fill plug location, exhaust, car needing to be level and the temp requirements of the fluid.

[kevm14]

Announcing the release of DEXRON-VI.

Of particular interest is this tidbit:

The content of this bulletin does not apply to manual transmissions or transfer cases. Any vehicle
that previously required DEXRON®-III for a manual transmission or transfer case should now use
P/N 88861800. This fluid is labeled Manual Transmission and Transfer Case Fluid. Power Steering
Systems should now use P/N 9985010 labeled Power Steering Fluid.

Ah. So my transfer case takes ATF. Except when they reformulated for DEXRON-VI, they decided to remove that requirement (perhaps to be better for actual transmissions), so they direct to another P/N. Which is probably some kind of DEXRON-III formulation. Good to know.

The article also has some characteristics of the new fluid, like change intervals (unmodified from DEXRON-III "for the time being" they say) and other performance things about the fluid compared to DEXRON-III. It sounds a lot better to me.

This is also interesting:

2006-2008 Transmission Fill and Cooler Flushing
Some new applications of the 6L80 six speed transmission will require the use of the J 45096 -
Flushing and Flow Tester to accomplish transmission fluid fill. It is highly recommended that the
clean oil reservoir of the machine be purged of DEXRON®-III and filled with DEXRON®-VI

They actually want you to flush the 6L80. Interesting. Which leads me to....

[kevm14]

The other thing that will confound Bill.

This article explains how to use the TransFlow flushing machine. Here is the first paragraph:

The J 45096 transmission oil cooling system flush and flow test tool replaces current tool J 35944-
A. J 45096 is a self-contained unit utilizing a 12-volt flow meter, shop air supply and DEXRON® VI
automatic transmission fluid (ATF). In the flush mode, transmission fluid is cycled through the
transmission oil cooling system. High-pressure air is automatically injected into the fluid stream
adding agitation to the ATF oil to enhance the removal of contaminated ATF oil and debris. In the
flow mode, an electronic flow meter is used to measure the flow capability of the ATF oil cooling
system. A digital display indicates the ATF oil flow rate in gallons per minute (GPM) along with the
amount of ATF oil in the supply vessel, supply vessel ATF oil temperature, machine cycles and the
operating mode. The supply oil vessel has 30 L (32 qt) capacity and the waste oil vessel has 32 L
(34 qt) capacity. The waste oil vessel is constructed of a translucent composite material that allows
the user to easily identify the oil level. The waste oil vessel can accommodate vacuum evacuation
and gravity draining. In the code mode, a random, encrypted code is generated that can be used
for verification of flow test results.

That's right, they force air into the trans to especially agitate and help remove old fluid and whatever junk is in the fluid. So there it is - GM themselves is not a believer in that old wives tale of needing to keep junk inside various valves and orifices because, somehow, that junk is holding the transmission together. I honestly can't speak for other manufacturers, but I doubt GM is alone in the pro-flush school of thought. Clean, uncontaminated fluid is of paramount importance.

The machine connects to the transmission fluid cooler inlet and return, which is what I would expect. They also imply that all GM transmissions can be flushed, as they list basically all of them in this article (this article is not specific to the STS or 5L50).

[kevm14]

Shift speeds vs throttle position vs gear. This seems dumb to publish because new calibrations may change this.

[kevm14]

And the capstone is another old wives tale hopefully debunked. That is, the idea of a specifically calculated, coordinated, engineered attempt for planned obsolescence. And by obsolescence, I mean failure by some amount of time or mileage.

I will admit that it can often look like they must have done this (Bob can vouch for this knowing how OEMs can sometimes specify a part to the point where it may compromise durability - but that is to save money on the part, not to "make sure it fails at the right time.").

The thing about this is, it is unreasonable to think there is actually an entire team set up to make sure certain components last through the warranty, but no further. When you stack up the manufacturing variation/tolerances, age, mileage, driving environment, driving style and maintenance, there is basically no way to reliably accomplish this. Maybe Bob can chime in having worked in Quality for a number of years. The idea that "they build 'em to last 100k and no more" is just complete ignorance.

Anyway, here is the statement, which is pretty clear to me:

Dealership Service Management Responsibility
Important: There may be situations where an assembly can be repaired, but due to customer
satisfaction reasons, an assembly replacement should be considered. The dealership should still be
prepared to provide the PQC with the information on the diagnosis. In these cases, the dealer
Service Management should contact PQC. PQC will contact the dealer's District Service Manager
(DVM) (in Canada, the District Service Manager (DSM)). The DVM/DSM then should communicate
back to the PQC that they have approved the assembly replacement. Then the PQC can contact the
dealership to advise them of the DVM's/DSM's decision and to approve the warranty claim.

The servicing technician must provide detailed customer complaint, conditions, diagnostic trouble
codes (DTCs) and other useful information with each assembly replacement. Only the service
technician has the detailed information required for proper root cause analysis and product
concerns correction. This information is very valuable in ensuring that the replacement assemblies
and current production parts help to continually improve our products. Therefore, the assembly
replacement templates have been modified to capture and record the dealership service
technician's diagnosis notes/comments in detail.

We are requesting ALL service technicians use this opportunity to help GM better understand how
and why a given component failed. For us, this is an opportunity to have direct and thorough
feedback from our technicians to engineering and thus improve the reliability and durability of both
OEM and Goodwrench® assemblies.

[bill25]

You have definitely miss-quoted me a couple times here:

High-pressure air is automatically injected into the fluid stream adding agitation to the ATF oil to enhance the removal of contaminated ATF oil and debris.

This is bad because it can potentially get debris stuck in places it shouldn't go, not because it is getting it all out.

GM themselves is not a believer in that old wives tale of needing to keep junk inside various valves and orifices because, somehow, that junk is holding the transmission together.

Nobody said the junk was holding the transmission together, but that the friction material from the trans clutches being in the fluid helped the clutches with friction. That friction material is not present after a flush, causing the trans to slip more.