Transmission Fluid Advice

16LT4 · August 17, 2019

2 hours ago, RE1 said:

Makes more sense now. Thanks.

Since I don’t have a drain plug, I’m gonna use the pump into the dipstick tube method next time.

Has the filter already been changed and pan/magnet cleared? If so, I don't see a problem with that. If not, you could order a new pan with a drain plug; I definitely wouldn't pull fluid without replacing the filter and cleaning the pan. Most wear is going to occur in the first 10k miles on these transmissions, after that, any particulate is just circulating through creating more wear particles, which create more wear particles, etc. When I dropped the pan on my F150, I couldn't even see the magnet under the literal ant hill of metal shavings (but that was at 143k miles, 70k of which was towing a 10k lb travel trailer to and on the beach, and had original fluid in it).

Edited August 17, 2019 by dukedkt442

RE1 · August 17, 2019

12 minutes ago, dukedkt442 said:

Has the filter already been changed and pan/magnet cleared? If so, I don't see a problem with that. If not, you could order a new pan with a drain plug; I definitely wouldn't pull fluid without replacing the filter and cleaning the pan. Most wear is going to occur in the first 10k miles on these transmissions, after that, any particulate is just circulating through creating more wear particles, which create more wear particles, etc. When I dropped the pan on my F150, I couldn't even see the magnet under the literal ant hill of metal shavings.

Yeah. Full transmission service recently at 94k miles (pan off, filter replaced, magnet cleaned, full fluid exchange).

Grumpy Bear · August 18, 2019

On 8/16/2019 at 10:42 PM, jay webb said:

for those saying dont let the dealer use "bulk" fluid ... the bulk fluid we carry for atf is dexron vi which is spec by gm.

I repeat this on just about every post on this topic. Dexron VI is a fluids PHSICAL SPECIFICATION and not its fluid TYPE. Just like 30W is a specification and not a type. Marketing has misused the words until the English speaking world no longer understands the meaning of words in general. The specifications for D6 fluids can be met with several different fluid TYPES and that stuff in the drum is at the bottom of the materials performance list. Meeting a GM specification for the fluid means it meets the BASIC SAE fluid specification requirements. Does NOT tell you what its made from. What it's made from is its TYPE.

BTW, not ALL 6L80E transmissions in all vehicles have dipsticks. Okay, not counting the one behind the wheel. :crackup:

KARNUT · August 18, 2019

My brother in law. The one that keeps his GM trucks and SUVs north of 200K miles. Just replace his transmission in his truck at 280K miles. He passed it to his daughter to go to college 4 years ago. Just this past week he pulled his firebird on a uhaul trailer from Texas to the boarder of Mississippi. A 6 hour trip. He just does routine maintenance. No problems.

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Praedator · August 18, 2019

3 hours ago, KARNUT said:

My brother in law. The one that keeps his GM trucks and SUVs north of 200K miles. Just replace his transmission in his truck at 280K miles. He passed it to his daughter to go to college 4 years ago. Just this past week he pulled his firebird on a uhaul trailer from Texas to the boarder of Mississippi. A 6 hour trip. He just does routine maintenance. No problems.

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People that only expect a vehicle to last 4-5 years and under 150K miles is beyond me. I have been a Tundra owner before purchasing this GMC. I hope I didn't make a bad mistake. I got rid of my Tundra with 230K on the ticker. The front end parts needed replacing. But the engine and transmission would have kept going forever I think!

I could have put the 2K into the Tundra but I simply wanted a new truck and I needed 4WD and my Tundra was not. But I couldn't afford the Tundra prices. So I found this GMC Crew Cab and listening to all these posts about longevity makes me a little nervous. I changed engine oil regularly and changed the transmission fluid once in that 230K miles on that Tundra! Granted it was an older model Tundra and I think they were a little more bullet proof than the newer ones.

Grumpy Bear · August 18, 2019

On 8/16/2019 at 10:42 PM, jay webb said:

A.) 3rd the mobil 1 fluid is recommend by the dealer due to the trans shutter issue, which is caused by the previous trans fluid getting contaminated via water, its very hydrogroscopic. the fix for the shutter is flushing the torque converter with the mobil 1 lv atf hp trans fluid.

B.) on vehicles with out a serviceable filter that still uses atf fluid the fluid exchange is the only way to exchange the fluid, most dont have dipsticks . yes there are fill plugs and fluid level check plugs/drain plugs. its 100% easier to do the machine and its the same thing.

A.) Here's a trust issue in practice. Like Microsoft you didn't sort it out before you sold it. Your deliberate actions cause the consumer a huge issue, then you do it right and want the consumer to foot the bill (hoping he/she makes it outside warranty) or run him around the block until he's dizzy if he doesn't, and....AND....believe you got it right THIS TIME.

B.) GM preaches the 5 micron rule and then creates a transmission (Terrain six speed) whose transmission requires complete disassembly to replace/service and basic maintenance component. A filter? Yep, GM has my best interest in mind.

Nanotech Environmental · August 18, 2019

On 8/16/2019 at 11:42 PM, jay webb said:

4th at the dealership i work at ( nearly 7 years as a tech) i have done hundreds of trans services. pan drops , fluid exchanges (not flushes). the machine we use to do a fluid exchange uses the vehicles own transpump to exchange the fluid. we tap into the system via cooler lines in series and run the vehicle with the machine filled with new clean fluid and it pumps the old out and sucks the new in. typically changes 14 qts. when you do a pan drop you only change about 6 qts in the system. it is not pressured by shop air or anything. it does not damage the trans.

the 2014-2018 trucks have a trans thermostat. in order to service these we have a special adapter that we use to tap into the system, there is a block on the side of the trans held on by 1 bolt, it has the cooler lines attached. we remove that bolt and that block install the adapter right at the trans and connect the machine to that adapter.

(bold) This is what I do and IMO, it really is the correct way to replace fluid. It's also the least messy method. I call this method a 'passive flush' . Totally harmless and totally replaces the fluid with little waste.

IMO, people worry about the filters and magnets un-necessarily. Trans filters aren't exactly 1 micron super filters; they really don't stop a lot. They just catch the big stuff and will likely never get plugged, especially if the fluid is kept healthy. Whatever ferrous metals get stuck to the magnet will stay stuck to the magnet for the life of the trans, so won't be an issue.
Fluid health is at least 80% of the equation in an auto trans. Keep the fluid healthy the trans will be happy. Maybe drop the pan every 150k miles* for a cleanout & you'll be fine.

*for normal light load driving. For severe service, the intervals can be increased.

1SLOW1500 · August 18, 2019

I agree fluid health is most important but that is based on debris but more so heat. Much of which is based of the tune then on the parts.
The best in the industry when it comes to trans and tunes as well as gm on the 6l80e all agree. Get your changes in and clean the magnet. Keep heat low. Base toy maintenance on use and temp.
But if you don't believe the hype. Go over to a trans based forum or as the pros.
Sorry to say this but it is true. A dealer mechanic normal does not have the experience with this say a pro big name trans shop or best tuners in the world or even GM techs.
I got in a arguement with buddy that is master tech at his GMC dealer over things like this all the time. In the end he just admitted he only knows the info they provided and is limited to his field.

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16LT4 · August 19, 2019

Little aside: The 2004-r GM trans, some argue, is horribly weak. Mine has lived behind an 11 second turboed 455 in my Olds, brutal neutral drops by the previous owner, and is currently pushing over 150k miles of hard street and strip abuse. So much abuse that the cast iron TC split its case and took me forever (and several trans drops) to find the root cause of its fluid leak. The trans’ guts, however, are still solid, 100% original, and hold up...I’ll let it sit for a month, and then go light it off like I hate it. I’ve towed with it, jumped with it, and melted a set of tires to the rims with it. Yet the “weakest” GM trans eats it. My secret on that one? Pan drops every 10k miles and lubeguard red every time, and a dedicated external trans fluid cooler parked in front of the aC condenser. I like to buy my vehicles north of 50k miles because I hate spending money, but then take them past 200k, never had a failure yet. Fluid is far cheaper than replacing hard parts.

Edited August 19, 2019 by dukedkt442

Grumpy Bear · August 19, 2019

20 hours ago, Nanotech Environmental said:

(bold) This is what I do and IMO, it really is the correct way to replace fluid. It's also the least messy method. I call this method a 'passive flush' . Totally harmless and totally replaces the fluid with little waste.

I am admittedly unfamiliar with the exact piece of equipment being used BUT unless that machine/device is FIRST removing 14 quarts and THEN adding 14 quarts back preventing comingling of fluids.....it isn't doing what you think it is.

You have a sippy cup of milk in the sink. The faucet is adding water via a straw through the lid while the over flow (sippy part) is allowed to run off the excess beyond it's capacity. It is a differential dilution. I'm not doing the math for you but it would take more than a standard refining drum (42 gallons or 168 quarts) of fluid to reach 90% turn over in a three gallon system.

If on the other hand it does remove the entire 14 quarts of fluid BEFORE adding back then you have an 85% exchange. 99.6% if you do it twice. 28 quarts.

Three drop and fills (6 quarts each) = 86% turn over using only 18 quarts. 36 quarts will get you 98%.

Simpler visual yet. Slowly pour 14 ounces of clean water into one 16 ounce tumbler full of milk while stirring and observe. Then put 14 ounces of water into a 16 ounce tumbler containing 2 ounces of milk and observe. Compare the two for opacity.

Edited August 19, 2019 by Grumpy Bear

Grumpy Bear · August 19, 2019

20 hours ago, Nanotech Environmental said:

Fluid health is at least 80% of the equation in an auto trans.

On this we agree but fluid health is more than just keeping it fresh and uncontaminated.

Keep it clean. That trans filter is a bit more efficient than you are giving it credit for. This is a hydraulic system. 5 mic is pretty standard for this service. Can I confirm that GM filters meet that spec? No.

Keep it cool. GM does not address this as it should in the 6L80E equipped trucks. Not even the max tow versions.

mookdoc6 · August 19, 2019

The Trans filter on the 8L90 is pretty much just a felt cloth able to catch shrapnel as for fine particulates not a chance....They don't filter like you think they do.

Grumpy Bear · August 19, 2019

18 minutes ago, mookdoc6 said:

The Trans filter on the 8L90 is pretty much just a felt cloth able to catch shrapnel as for fine particulates not a chance....They don't filter like you think they do.

Quite possible Mook. I don't know it all, right? Of course I kind of said that when I mentioned I could not confirm the GM filter efficiency. Have a good' n.

1SLOW1500 · August 19, 2019

My kids diaper doesn't catch the big blow out but I still change it out when I am in there. [emoji38]
It is easy to add a inline filter as many have done.

I believe like many things we base worth of the effort with cost and importance. Like tires I don't care they are a wear item.

These tans are huge cost. And labor cost. And that is assuming just the parts not the fluid and converter.
That said why not drop and replace?
Hell do it once and add a pan with a drain. Then save money in time over the dealer flush. As GB said.

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mookdoc6 · August 19, 2019

8 minutes ago, 1SLOW1500 said:

My kids diaper doesn't catch the big blow out but I still change it out when I am in there.
It is easy to add a inline filter as many have done.

I believe like many things we base worth of the effort with cost and importance. Like tires I don't care they are a wear item.

These tans are huge cost. And labor cost. And that is assuming just the parts not the fluid and converter.
That said why not drop and replace?
Hell do it once and add a pan with a drain. Then save money in time over the dealer flush. As GB said.

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I agree it's what? 25.00 bucks for the filter and O-ring....But they are definitely not on par with the spin on type for Allisons. They should be though seeing as how the MFG's are having such issues with the Fluids, and 8+gearbox speeds and installed harnesses that seemingly can't handle the juice or basically Hydraulic fluid that it is absorbing water?