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Changing you transmission fluid...SOLVED!!!!!!

23341 Views 12 Replies 8 Participants Last post by  jcbecker28
I know, most say, "take it to the dealer".

I like working on my vehicles, and honestly, I trust something is done, beyond a shadow of a doubt, only if I do it. Additionally, I enjoy figuring out a challenge. This is something you have to do one time. It does not have an impact on the vehicle in any way, shape, or form, if you do it correctly...and that whole correctly part isn't difficult. I typed this up because I wanted to show just how easy it is to do.


GM's tamper-resistant transmission design makes it downright unpleasant, but not impossible, to change it. However, "lifetime" transmission fluid is utter BS. Heat is the enemy, and once transmission oil breaks down, the innards are not far behind.

Based on where the OEM fill port is located, and how you are supposed to fill while it is running and, yeah. I'll have the burn on my left forearm for a few months, probably.

/end mini-rant

With your own fill port, the engine need not be running, nor hot, and you're not going to spill more transmission oil on you/the floor than you get into the case.

You need:

Torx T40 bit
10mm socket, extension, and wrench
10mm box-end wrench. A simple one, as the ratcheting type, while very nice to use, are too large for two of the bolts. Trust me on this. The bolts are at the LR and RR corners, kind of above the exhaust. You'll see.
Six quarts of Dexron VI
New transmission filter...I mean, you're gonna be in there anyway, might as well do it one time and be done with it.
Drain pan - very preferably marked every quart so you know exactly how much comes out. A $2 bucket works well, as with the car jacked up really high, there's plenty of room.
A drill and enough bits to gently step up from a pilot hole to 1/2". I used five bits, which was plenty.
One of these: A Fumoto F107N drain plug I've had several of these over the past 25 years, and have never, EVER, had any issue...ever...with one, and I've used them for both engine oil and transmission oil. In fact, I may put one on the N*, to make oil changing a no-tools job.
1 12mm x 1.75 nut. They're 2 for $0.80 at Lowe's.
Some 'pooky'. Your gasket making goo of choice, just make absolutely certain it's oil-resistant.
A couple of garage rags which have no metal filings in them, yet you have no problem throwing them out after they're saturated in oil.
A small manual pump. Hazard Fraught, er, Harbor Freight, has one for $5-$7, and it's perfect for this application. The included hose is a perfect fit for the drain valve's nipple, and mine has yet to leak after four or five uses...I'm shocked, and will likely get a decent one at some point, but this one is my dedicated petroleum pump. Here it is: a simple hand-operated transfer pump

Put the car on four jackstands, as high as you can get it because you're going to be under it, dead center, and you don't want to be either cramped for space or have any unnecessary risk of it falling on you.

Drain all the fluid into the marked catch pan/bucket. The Torx drain plug is torqued much tighter than you'd expect. Don't panic, but you don't have to put 40 lbs. of torque back on it when reinstalling, like the factory did. Again, it's a very good idea to use a catch pan which has markings every quart. I used an old bucket and marked it with Sharpie after measuring 8 quarts of water. I'm repeating myself, I know, but remember, you can't check the fluid level, so unless you have a leak, then put back the same amount you took out. Might be 5 1/4 quarts...might be 5 1/2...might be 6. Don't guess!!! A replacement transmission is $2K+!

There are a bunch of bolts holding the pan onto the transmission's case. Undo all of them, after draining. I like to leave the last two to be on opposite sides, but in the same location front-to-back, so I can hold the pan while removing them. You'll receive a transmission fluid hair rinse only one time before you figure out how, usually, to prevent it. Transmission pans didn't used to have drain plugs, OEM, which is why I've put in a few of my own this same way.

Slowly remove the pan. You'll have some drips, that's normal, so it's nice to have a slab of cardboard under there. Be careful with the gasket! If OEM, it's likely rubber, and much more resistant to tearing than cork. I have a cork one because I had the filter replaced a few weeks back. I wish I'd asked them to reuse the same gasket, but I cleaned and pookied mine on both the pan's surface side and the side which meets the transmission case. Not much, just a little, so there should not be any leaks.

Yes, the bolts holding the pan to the transmission case likely seem alarmingly loose. Because of the number and spacing of them, they do not need to be torqued much past not-gonna-fall out. When replacing the pan, resist the temptation to crank down on these, as you can actually create leaks this way by squishing the gasket. This area is under zero oil pressure, the gasket is there to keep the oil from escaping and road grunge from entering.

Once the pan is out, you can replace the filter, if you have one, otherwise, clean the nicely large, flat magnet in the bottom. All that stuff is clutch leavings, it's normal. I've found a paper towel...or good for this, so you can see how much comes off and you're highly unlikely to introduce any bad stuff.

Now that you have the pan out and cleaned up a bit, using a punch and hammer, make a mark near the front right corner, as it is oriented on the transmission. I have the area circled, below. This interferes with nothing, is easy to access, and is not in harm's way. Not on the corner, a couple of inches back, and about midway between the pan's floor and the mounting lip.

Drill a pilot hole, and using gradually larger bits, make it ½”. Make certain to get every single speck of metal out of the pan! I took my Dremel after drilling, and cleaned up the hole's slightly ragged edges. 45 seconds with some sandpaper would do the same. To catch many of the filings, I put a wadded up paper towel in the pan, but this was overkill, as I wiped the whole thing down, afterward, and had it as clean as the day it was installed.


Time to put it all back together! Dab some pooky (gasket goo) on the exterior washer, the pan, and I put a little on the inside, too, on the thread closest to the pan, because I'm paranoid, and never want to have to concern myself with a drip. I wanted to make certain there wasn't any chance of oil escaping via the threads or of the bolt backing off over time. It's unlikely, but y'never know.

Reinstall the pan, be patient with those two rear corner bolts, and you'll find, you can open the valve, after putting the siphon hose on the nipple, and it'll take all of maybe five minutes to pump in the same amount of fluid you drained, but it'll be new and red, not black. At least mine didn't smell burned.

I measured right at 6 quarts came out of mine, including the little bit left over in the bottom of the pan which cannot drain through the plug on the bottom of the pan. Fortunately, I have a 3 quart jar, which is clear, so I put three fresh quarts in it at a time, refilling only once. A decently sized jar is good for this, as the quart bottles are easy to tip as they empty.

After you've pumped the fluid back in, close the valve, remove the hose, wipe everything down, and you're done! It couldn't hurt to put both pump hose ends in the container you were using, in case they drain a little.

Yes, I know mine is a mess...there is a small oil leak from I think the rear corner of the right valve cover, but I cannot see the bolts. I'm diving back in there, today, because I'm tired of having cardboard laying on the floor of my side of the garage.

Here is a picture of the access and how much room there is with the new fitting.

Total cost, parts only, < $35. This doesn't include a new filter or any supplies, just the parts which you're going to install for this modification.

Also, you've made this a zero tools job, once you get the car in the air, as you can use the new valve as both the drain and the refill port. I'm going to put a vacuum hose cap on it, or something, to keep it relatively clean, but if you use it as a drain, it'll self-clean, to a degree. I'd wager 30 seconds with a Q-tip would remove most any road grunge, too.

If you have any questions, just ask. Yeah, this took about three hours, but I was being über-careful, taking pictures (having to clean up before working the camera), making mental notes, looking to see if there was a different way, and the like. Plus, I wanted to make it as easy as possible for anyone else wanting to do it. For example, the LR pan bolt...I wasted a solid 15 minutes on that before realizing a conventional 10mm box-end wrench was the only way it was going to work. First, though, I had to try every single wrench/socket/U-joint combo, along with trying to pry the exhaust just ¼" out of the way...nope, not gonna happen.
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Pretty nice write-up; one correction (you probably just made a transcription, 'typo'). You need to use Dexron VI ATF (you listed Dexron IV).

And I proofread it at least three times, too....

What kills me is, never used to transpose numbers/characters like this.
What prevents fluid from draining back down whole attempting to refill it? Does the pump have a check valve that prevents this? Also although unlikely I'd hate to think what happens if something like a branch gets run over and hits the valve dumping the fluid (highly unlikely I know but still plausible),..

Other than that kudos I may consider doing this myself.
Anti-drainback valve in the hand pump. A very rudimentary one, but it works remarkably well.

I oriented the drain valve so that it's effectively impossible for anything to smack it, turn it, and dump the oil. And while unlikely, it's not impossible.

I had one of these valves on a lowered 1985.5 Nissan 720 regular cab pickup...hey, it was the late-80's, lowering was the thing, though mine was only about a 2" drop 'cause I actually used it for work...and on a gravel/rock road in the middle-of-nowhere Idaho, the lever was simultaneously hit by a rock and turned, dumping about 2.5 of my 4 quarts on said 'road'. I saw the oil pressure light flicker, killed the engine, stomped on the brakes, got under there as fast as I could, and stemmed the flow.

Coasted down the mountain...I had just come over a a long abandoned farmhouse. After yelling "hello" and "anybody here" for about five minutes, reducing the likelyhood of being shot, I found one quart of no-name oil, in a can, unopened, in what used to be a shed/workshop. I'm surprised it was still standing, honestly.

I left a $5 bill under a rock on this same table, just in case, put the quart in, and it was enough to keep the light out until I made it to, ironically, Arco, ID.

This is the only time it's happened, and admittedly, I had the valve's handle in a less-than-ideal position for this happening. I can't imagine it happening again, and with oil pan threads, unless you shim with washers, it's oriented the way it's oriented.
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Nice write-up! I'd have to second the cleanliness comments. GM touted the clean-room assembly techniques employed with this series of transmissions. Other manufacturers (like BMW) have thought well-enough of it to use it in several of their cars.

It's certainly not perfect, but I do like it. I have to admit, I don't do much of my own service on our STS's. That's for my toy car - this afternoon I'm playing with the clutch (R&R) on my Triumph TR6.
One thing I would like to know is what class of clean room they are dealing with.
Robots only in the clean room lol. Good write up.
Clean room or not, you still have manufacturing swarf (little bits and pieces from the machining process), clutch pack wear and other materials, that would be nice to be able to easily remove (along with a filter replacement) that wouldn't require a trip to the dealer (or transmission shop) or the convoluted procedure mckellyb so generously provided. I want my dipstick tube back (or at least an easier to properly check and refill port).
I know this is an old thread but how much quarts does the 5l40e take?
Should state in the owners manual under fluid capacities.
Depends on whether it's a 'dry fill', I mean from the system being dry, or a drain/refill.

Also, if you can drain the pan and the converter, that'll be different, too.

This thread's less than a month's not "old".
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