ATF Lab Results, Dexron VI, 43k miles on fluid

donjetman · May 5, 2022

I recently changed the ATF & filter. I took a sample with a JG Lubricant Services used oil analysis kit. They use Polaris Laboratories. Sent it in and 5 working days later here are the results. This is the same fluid and filter as before (see result #1).

Lab flagged the viscosity of 5.6, so I called Tom Johnson of JG Lubricant Services. Tom is co-owner of JG Lub. He spent 30 yrs with GM/Allison as a fluids engineer. He said when viscosity gets to 5.5 they recommend changing the fluid. When viscosity gets to 5.0 bushings etc start to wear. So my timing this fluid/filter change worked out good. Not too early, not too late.

Tranny has 174k miles since new. 43k miles ago, while doing the engine rear main seal job, I replaced the original torque converter as a preventative mx item. That was the last time I changed all the fluid and the filter.

gooffeyguy · May 5, 2022

So the factory severe maintenence schedule is spot on in your case at 45k miles

Geotrash · May 6, 2022

Thanks for sharing, Don. I will do the same when I change my fluid next.

swathdiver · May 6, 2022

That jives with my fluid analysis too.

m1949 · May 6, 2022

donjetman said:
I recently changed the ATF & filter. I took a sample with a JG Lubricant Services used oil analysis kit. They use Polaris Laboratories. Sent it in and 5 working days later here are the results. This is the same fluid and filter as before (see result #1).

Lab flagged the viscosity of 5.6, so I called Tom Johnson of JG Lubricant Services. Tom is co-owner of JG Lub. He spent 30 yrs with GM/Allison as a fluids engineer. He said when viscosity gets to 5.5 they recommend changing the fluid. When viscosity gets to 5.0 bushings etc start to wear. So my timing this fluid/filter change worked out good. Not too early, not too late.

Tranny has 174k miles since new. 43k miles ago, while doing the engine rear main seal job, I replaced the original torque converter as a preventative mx item. That was the last time I changed all the fluid and the filter. View attachment 369690

Good ”in-the-field” info! Thanks.

donjetman · May 6, 2022

The vehicle doesn't ever see any severe duty service. No towing. Mostly rural and hwy driving. No stop n go. I drive the speed limit and never hot rod it.

43k miles ago, pretty much "ALL" the atf got changed (11 qts) because I not only dropped the pan, I changed the torque converter too which holds 5 qts.

This time I only changed the 6 qts that comes out when the pan is removed.

I'm planning my next change for about 25K miles from now, which is at 200k miles on the odometer.

jmil1974 · May 10, 2022

Fluid changes and cleaning (TB, intake, top end) are the most important maintenance items on cars now...if you want it to last. Well done.

thingraylinetah · May 12, 2022

Very informative.

j91z28d1 · Mar 19, 2023

interesting.. do you know what the viscosity of new dexton 6 is?

I just got some results back a few weeks ago, different lab(black stone) and different gm tranny(2ML70). first one of its type they had tested. so nothing really to compare to but looking at it, viscosity is shown at 100c being 5.55. only 9k since I changed the fluid and filters, all 12qt comes out with these trannys. (no tq converter) but I just got back from my first long tow with this vehicle. 2k miles towing a car, I'd guess 6k lbs. since I was sending the car's sample out after a track day, I sent some of the trucks atf too. they didn't mention anything about viscosity looking low, but if 5.5 is considered low for a 6L80, seems like it would be low for just about all autos.

which left me wondering what fresh fluid would test at, since mine is only 9k old and my tranny Temps never budged over 167deg the whole trip. so it really shouldn't have beat up its fluid, but also fluid change is way cheaper than a rebuild haha. worth erroring on the side of to often. especially with an odd ball tranny that might be difficult to find a rebuilder.

donjetman · Mar 19, 2023

j91z28d1 said:
interesting.. do you know what the viscosity of new dexton 6 is?

I just got some results back a few weeks ago, different lab(black stone) and different gm tranny(2ML70). first one of its type they had tested. so nothing really to compare to but looking at it, viscosity is shown at 100c being 5.55. only 9k since I changed the fluid and filters, all 12qt comes out with these trannys. (no tq converter) but I just got back from my first long tow with this vehicle. 2k miles towing a car, I'd guess 6k lbs. since I was sending the car's sample out after a track day, I sent some of the trucks atf too. they didn't mention anything about viscosity looking low, but if 5.5 is considered low for a 6L80, seems like it would be low for just about all autos.

which left me wondering what fresh fluid would test at, since mine is only 9k old and my tranny Temps never budged over 167deg the whole trip. so it really shouldn't have beat up its fluid, but also fluid change is way cheaper than a rebuild haha. worth erroring on the side of to often. especially with an odd ball tranny that might be difficult to find a rebuilder.

Depending on the brand, Dexron VI starts life (virgin) at a viscosity of 5.8 to 6.3. If it were mine I would drain/condemn the atf at 5.4 and below. By 5.0 bad things start to happen according to Tom Jonson of JG Lubricant Services. He owns JGLS, is an x-GM fluid engineer, and I use their used oil/atf analysis kits for all of my used "ATF" analysis on all my vehicles, mainly because he is available on the ph to discuss the results if I have questions. They use Polaris Labs just like Oil Analyzers Inc/Amsoil.
Valvoline Dexron6 specs
Mobil Dexron6 specs
Amsoil ATL

ATF Lab Results, Dexron VI, 43k miles on fluid

donjetman

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gooffeyguy

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m1949

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donjetman

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jmil1974

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thingraylinetah

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