Transmission Fluid Change Denali XL

[intheburbs]

Geeze, I didnt mean to get you on the defensive! My opinion to anyone is if they tow heavy and frequently the trans is wearing at an accellerated rate and be prepared for a trans replacement and purchase one designed to tow. Temps increase in auto's from slippage/friction not from "lockup", he noted temps "out of the norm" for his vehicle, I didnt mean to imply imminent failure. Now based upon your pic's, temps, RPM i think you should be carrying a broom and wheelbarrow/kittylitter to assist the towtruck with cleaning up your mess. I dont think you should be proud of having to run that thing like that, more lucky that it hasnt grenaded yet? Oh and i allmost forgot, If you ever decide to sell your vehicle dont forget to to word the for sale sign as "generally abused the hell out of it"

Not defensive at all. I'm simply commenting on people overreacting to slightly elevated transmission temperatures.

Oh, and another helpful hint - the 6L90 is already "designed to tow."
And regards to "RPMs," notice in the pic of my instrument cluster - no redline on the tach. The 6.0 motor loves to rev. Do a little Googling and see where the torque and hp peaks are. Hint: at 4k RPM, I'm still below the torque peak.

And yes, I do work my trucks hard. They're tools, and I use them like tools. I'm neither proud nor embarrassed about running my trucks the way I do. I run them within their designed operating parameters.

My 2008 truck has 190k miles, not counting fluid changes and tires, I've spent about $150 in repairs over the last five years. The entire power train is all original.
My 2001 truck has 250k miles. My best friend now owns it. Also has the original engine and transmission. I might have grenaded a few rear ends by towing a little heavy....

And no, it's not luck. I'm very meticulous about maintenance and fluid changes. I also know the capabilities of my truck. It also helps that a friend of mine is a transmission validation engineer at GM, and he actually worked on validation of the 6L80/90 transmissions.

Funny thing - I've been towing for almost 15 years. Haven't had a transmission fail in that entire time. I wonder why that is...

 

[swathdiver]

From the Useless Information thread, post #290: https://www.tahoeyukonforum.com/threads/useless-information.97483/page-29

With the weather warming up there's been talk of transmission temperatures and some fellas have been adding and or upgrading external coolers to keep the temperatures in line.

The 6L80s normal operating temperature is between 160 and 200 degrees. This corresponds with the HOT check on the dipstick when checking the fluid level. Cold check temperatures are between 80 and 90 degrees and also have a corresponding mark on the dipstick; mine anyway.

The temperature range for the Service Fast Learn Adapts procedure is 158-212 degrees.

If the transmission's temperature reaches 266 degrees for 5 seconds the "Transmission Hot Idle Engine" warning will display on the DIC.

Code P0218 (Transmission Fluid Overtemperature) will set if the fluid is greater than 270 degrees for one minute. On a side note, the shop manual says trailer towing should occur in D4 to ensure the cooling system functions normally.

The Flash Point for AC Delco's Dexron VI fluid is 401 degrees.

There is a transmission oil life monitor within the Transmission Control Module and is visible and able to be reset with the Tech2. I reckon that it is also based on engine revolutions and transmission temperature, similar to the Engine Oil Life System.

These trucks were literally designed to tow across Death Valley...

 

[Fless]

There is a transmission oil life monitor within the Transmission Control Module and is visible and able to be reset with the Tech2. I reckon that it is also based on engine revolutions and transmission temperature, similar to the Engine Oil Life System.

Does the 4L60 have a transmission oil life monitor, too? Too cold to go outside and connect the Tech 2 to check...

 

[swathdiver]

Does the 4L60 have a transmission oil life monitor, too? Too cold to go outside and connect the Tech 2 to check...

I don't know. Do let us know though when it warms up!

 

[Fless]

I will do that once things warm up a bit. The official low this morning at DIA was -6° F.

So much fun to cruise through all the info the Tech 2 shows, and use its tools.

 

[thompsoj22]

Not defensive at all. I'm simply commenting on people overreacting to slightly elevated transmission temperatures.

Oh, and another helpful hint - the 6L90 is already "designed to tow."
And regards to "RPMs," notice in the pic of my instrument cluster - no redline on the tach. The 6.0 motor loves to rev. Do a little Googling and see where the torque and hp peaks are. Hint: at 4k RPM, I'm still below the torque peak.

And yes, I do work my trucks hard. They're tools, and I use them like tools. I'm neither proud nor embarrassed about running my trucks the way I do. I run them within their designed operating parameters.

My 2008 truck has 190k miles, not counting fluid changes and tires, I've spent about $150 in repairs over the last five years. The entire power train is all original.
My 2001 truck has 250k miles. My best friend now owns it. Also has the original engine and transmission. I might have grenaded a few rear ends by towing a little heavy....

And no, it's not luck. I'm very meticulous about maintenance and fluid changes. I also know the capabilities of my truck. It also helps that a friend of mine is a transmission validation engineer at GM, and he actually worked on validation of the 6L80/90 transmissions.

Funny thing - I've been towing for almost 15 years. Haven't had a transmission fail in that entire time. I wonder why that is...

Cant argue with your real world results! It is a remarkable vehicle history and i hope to reap some of those memories also! That is a beautiful travel trailer setup!

 

[Thankful ForGrace]

I appreciate the info and lack of negativity on this thread. Well done! I would ask for the same in response to my question . I plan to do a drain and fill with new filter and pan with drain plug. ('07 xl with 6.2) Would it be better to open the trans line (or extract from fill tube) for the drain and replace the filter after some fresh fulid has been added or first do the pan drop and filter with the additional two drain and fills using the plug? TIA

 

[PG01]

I appreciate the info and lack of negativity on this thread. Well done! I would ask for the same in response to my question . I plan to do a drain and fill with new filter and pan with drain plug. ('07 xl with 6.2) Would it be better to open the trans line (or extract from fill tube) for the drain and replace the filter after some fresh fulid has been added or first do the pan drop and filter with the additional two drain and fills using the plug? TIA

I would dump via trans line until red color then filter, then top off. Depending on your truck tho, how do all those lines look? Rusty? Corrosion? Has the fluid ever been changed? Filter? Many variables with diff trucks/drivers etc. My 2 cents

 

[Meccanoble]

So to those of you that say we should get a transmission built for towing, I would assume that applies to the boosted crew and anyone else that likes to drive hard. If our trans goes bad, would it be better to rebuild or is there a version we can add to the NNBS that is better built for towing? If we want one rebuilt that would be better for towing or more abuse, what should we be upgrading? Torque converter?

 

[thompsoj22]

Just do a search 4L80E towing transmission, Summit racing has a well defined build inventory to inform you of what is replaced/improved. I am not part of the HP driveshaft twister club, But when i pull the grade from bishop to mammoth the first 23 miles are tough, our travel trailer weighs approx 5k loaded and everything in the driveline is put to the test. It is a paradox to replace the trans as preventive maint or wait for the big bang and potentially ruin a vacation. o8 yukon denali xl1500.