05 Escalade just hit 100k miles, ok to change tranny fluid?

[nonickatall]

I overhaul automatic transmissions in Germany and can tell you from my experience:

Oil in an automatic transmission should be changed at least every 50,000 km (30.000mi), under heavy conditions e.g. in frequent trailer operation also earlier.

The following is the background: The lubricating effect of oil is created by long chains of hydrocarbon molecules that slide past one another. In an automatic transmission, these molecular chains are subjected to high mechanical loads and break. The oil loses its lubricity and hydraulic stability over time. This is often reflected in poorer or rougher gear shifting behavior.

From a certain level of oil wear, the automatic transmission also wears out more.

And i state: Next to not good use, like permanent kickdown, or switch to neutral at the traffic light, or not to warm up the transmission before excessive acceleration, deferred maintenance, in form of oil change are the most common reasons, why automatic transmissions fail too early.

Many are afraid of an oil change at a transmission and refrain from it. That's wrong!

It is absolutely not necessary to open the unit and replace the automatic transmission filter every time, because in an automatic transmission there is neither so much abrasion, nor so many lumps that the oil filter would become clogged. And if, your unit is near the end.

So it is absolutely enough to change the filter all 2 oil changes, or even never.

Better you change your oil all 20.000mi without change the filter, than after 100.000 miles, before an overhaul, because someone tell you: That is the last thing you can try..

Therefore, you can change the oil quite well with this method:

https://www.cadillacforums.com/threads/transmission-fluid-change.154002/

This flushing is better than just draining the oil, because at least half of the oil is in the transmission and not in the oil pan. It is in oil passages, pistons, torque converter, oil cooler of the automatic transmission located. This oil you don't get out of your unit, when you just take the pan off.

That's why some workshops offer expensive gear oil flushes, which I don't think make any sense, because they are expensive and you can do it yourself.

Even a layman can do that. Just these three points are important!!!:

1. Use the right automatic transmission oil for your unit, with the right specification for the gearbox. As far as I know, on GM vehicles like Tahoe and Escalate, that's Dexron VI.
2. It is essential to ensure that no foreign particles are introduced into the automatic transmission, so ensure absolute cleanliness when filling.
3. And definitely pay attention to the correct filling quantity, which is relatively easy with the method I linked. When you have changed the transmission oil, the transmission has to be warmed up properly by driving, and then the automatic transmission oil level must checked with the engine running in P on a level surface.

If you do this method and watch the 3 points, it's not magic at all.

I would like to end with a quote from the famous German rally driver Walter Röhrl, who once rightly said:
"Cars cannot be treated like people, cars need love."

In this sense: Have fun with the smooth shifting behavior after an oil change and the good feeling that you did anything to service your unit, to keep it in service for a long time..

Excuse my bad English...

 

[SnowDrifter]

I personally hate the cooler-line-drain method. Apt to run the pump dry and shove air through the torque converter and hydraulics. Then you're spending the next day trying to purge the air out. Fiddling with those things is also likely to un-seat an o-ring and cause a leak, or wear out those dinky little moon clips and mess affect the retention. My method is to use a fluid extractor like a mityvac, shove it down the dipstick tube, and extract that way. Or, if you have an older rig with a drain plug in the pan - just use that. Be mindful not to over torque though - they like to strip out.

3-4 drain/fills from the pan will get you to pretty new fluid. The transmission is what... 12 quart capacity, and you'll get 3-3.5 out of a drain/fill of the pan?
Assuming 3 quarts from a drain/fill... Math: 1-(1-3/12)^n*100% = %New Fluid, where n is the number of drain/fill cycles. 4 will get you to ~70% new fluid, which is plenty fine.

I drain/fill mine once a year regardless. 170k and still on the original 4Lslippy. The way I see it: I won't get all the old fluid out. But I do that operation often enough that the fluid isn't old and fouled, so I just keep it new. Trans always shifts the same - no change in feel before/after the fluid change. If it shifts notably different - "better" - your old fluid was past its useful service life and you should be doing that more often.

 

[nonickatall]

I personally hate the cooler-line-drain method. Apt to run the pump dry and shove air through the torque converter and hydraulics. Then you're spending the next day trying to purge the air out. Fiddling with those things is also likely to un-seat an o-ring and cause a leak, or wear out those dinky little moon clips and mess affect the retention. My method is to use a fluid extractor like a mityvac, shove it down the dipstick tube, and extract that way. Or, if you have an older rig with a drain plug in the pan - just use that. Be mindful not to over torque though - they like to strip out.

3-4 drain/fills from the pan will get you to pretty new fluid. The transmission is what... 12 quart capacity, and you'll get 3-3.5 out of a drain/fill of the pan?
Assuming 3 quarts from a drain/fill... Math: 1-(1-3/12)^n*100% = %New Fluid, where n is the number of drain/fill cycles. 4 will get you to ~70% new fluid, which is plenty fine.

I drain/fill mine once a year regardless. 170k and still on the original 4Lslippy. The way I see it: I won't get all the old fluid out. But I do that operation often enough that the fluid isn't old and fouled, so I just keep it new. Trans always shifts the same - no change in feel before/after the fluid change. If it shifts notably different - "better" - your old fluid was past its useful service life and you should be doing that more often.

When I rebuild a transmission, the transmission is wet, but empty. I dip the parts in oil, to give a start lubricant, but the unit and the torque converter is empty. That was never a problem. You fill in the needed oil quantity, start the engine, shift trough every gear and finish, the air is gone. Never had a problem like that you describe.

And as long as drain only in idle and P, until you see air and stop immediately the engine, there can be no damage to the unit. A automatic transmission has not pressurized plain bearings, like the crankshaft, or the camshaft in an engine, which you damage very fast, if not enough oil is in and the oil pressure fails.

Your mathematics ist great. But this is the major disadvantage of your method, because you must drain and refill 3 Quarts, than you must run the engine, where your mix your old and new oil and then you drain the next 3 quarts, where only 1,5 Quarts old oil are contained. Mathematically you must train endless until you have 90% oil refill. The other method pump your pan empty, also 3 Quarts, you refill, and you continiue pump old oil with fresh oil outside the unit, because you continiue pump oil trough your unit. You will as well mix old oil with new oil, but I think when you drain with your method 4 times you probably have 50% new oil. With the method i prefer, you have 90%

But at least you are right, if you do that regularly, it is not a big problem and works as well.. The cooler line drain work a bit better, even if never get all oil out of the unit.

At least if you like this method more, do it. The important is, you change oil once the year and your transmission will thank it with long lasting function.

And at least. which method you choose is anyway, even if you only drain 3 Quarts once and refill, but you do that 4 times the year.

Everything is better, than to drive 100,000 Miles with the same oil...

 

[rockola1971]

I overhaul automatic transmissions in Germany and can tell you from my experience:

Oil in an automatic transmission should be changed at least every 50,000 km (30.000mi), under heavy conditions e.g. in frequent trailer operation also earlier.

The following is the background: The lubricating effect of oil is created by long chains of hydrocarbon molecules that slide past one another. In an automatic transmission, these molecular chains are subjected to high mechanical loads and break. The oil loses its lubricity and hydraulic stability over time. This is often reflected in poorer or rougher gear shifting behavior.

From a certain level of oil wear, the automatic transmission also wears out more.

And i state: Next to not good use, like permanent kickdown, or switch to neutral at the traffic light, or not to warm up the transmission before excessive acceleration, deferred maintenance, in form of oil change are the most common reasons, why automatic transmissions fail too early.

Many are afraid of an oil change at a transmission and refrain from it. That's wrong!

It is absolutely not necessary to open the unit and replace the automatic transmission filter every time, because in an automatic transmission there is neither so much abrasion, nor so many lumps that the oil filter would become clogged. And if, your unit is near the end.

So it is absolutely enough to change the filter all 2 oil changes, or even never.

Better you change your oil all 20.000mi without change the filter, than after 100.000 miles, before an overhaul, because someone tell you: That is the last thing you can try..

Therefore, you can change the oil quite well with this method:

https://www.cadillacforums.com/threads/transmission-fluid-change.154002/

This flushing is better than just draining the oil, because at least half of the oil is in the transmission and not in the oil pan. It is in oil passages, pistons, torque converter, oil cooler of the automatic transmission located. This oil you don't get out of your unit, when you just take the pan off.

That's why some workshops offer expensive gear oil flushes, which I don't think make any sense, because they are expensive and you can do it yourself.

Even a layman can do that. Just these three points are important!!!:

1. Use the right automatic transmission oil for your unit, with the right specification for the gearbox. As far as I know, on GM vehicles like Tahoe and Escalate, that's Dexron VI.
2. It is essential to ensure that no foreign particles are introduced into the automatic transmission, so ensure absolute cleanliness when filling.
3. And definitely pay attention to the correct filling quantity, which is relatively easy with the method I linked. When you have changed the transmission oil, the transmission has to be warmed up properly by driving, and then the automatic transmission oil level must checked with the engine running in P on a level surface.

If you do this method and watch the 3 points, it's not magic at all.

I would like to end with a quote from the famous German rally driver Walter Röhrl, who once rightly said:
"Cars cannot be treated like people, cars need love."

In this sense: Have fun with the smooth shifting behavior after an oil change and the good feeling that you did anything to service your unit, to keep it in service for a long time..

Excuse my bad English...

You left the part out where a well worn tranny has a complete flush and new fluid causes the seals to swell and then they leak and the tranny is due for a rebuild a few minutes later. Which is of course great business for a tranny shop then.

 

[nonickatall]

You left the part out where a well worn tranny has a complete flush and new fluid causes the seals to swell and then they leak and the tranny is due for a rebuild a few minutes later. Which is of course great business for a tranny shop then.

How should a seal which works for 10 years and 100000 Miles, when it comes in contact with new oil swell and fail?

That is absolutely non logic.

But bearings, clutches, pistons and their seals wear out more, when the oil no longer has lubricity, because it is old.

And from my experience unit dies because of worn out clutches, brocken parts, destroyed gears, or in case of the Tahoe and Escalate gearboxes, worn out valve blocks.

What you describe is probably the result of people with units with bad shifting behavior. Their gearbox starts to have problems at some point, because it's worn out, probably advantaged of the old oil, then they go to the garage to describe their problems and the mechanic says: "We can try to make an oil change, that can help. Because experience is that very old oil makes a bad shifting transmission."

Then they make an oil change, but the gearbox dies shortly later, because it was just worn out.

And then you infer that fresh oil destroyed a gearbox.

Come on