2016 6L80 ATF analysis

16LT4 · October 25, 2022

My '16 5.3 CCSB 4x4 currently has 105,500 miles on it. Back in September on a quick weekend trip NY-OBX, I noticed a slight 100 RPM hunt going up slight inclines at 68 mph in 6th gear and V8 mode. I'd never noticed it before, but hadn't driven it down there with the new exhaust on the truck, either. If it weren't for the slight change in exhaust note, I never would have noticed the slight tach needle movement. I figured it was torque management, but to be sure, I performed a drain/fill when I got home at 104,750 and sent it in to blackstone.

I changed the filter and performed 3 drain-fills at 72k miles with Castrol D6, adding a bottle of Lubegard on the final fill. At ~92k miles last summer, I performed a single drain-fill with Redline D6, again with a bottle of LG, and "flipped the pill" in the AT T-stat. In January 2022 I installed the updated 70*F ATF T-stat at 99k miles. This most recent time, I used AC Delco FS D6, a bottle of LG, and a tube of Shudder Fix for good measure. The slight RPM hunt vanished immediately.

AFM is enabled, I always drive in "D" (never M5), and the truck spends probably half its life in V4 mode. I occasionally tow and haul much more in the bed than the truck is rated for, loading firewood in the bed until it hits the bumpstops, and then keep loading. With very little exception, the truck is driven at least a half hour every time I start it, and has been used for my long distance (400 mile round trip work commute) at least a half dozen times since August due to fuel prices and is cheaper to run than anything else I own (E85 is a dollar cheaper per gallon than 87). I seldom "floor it," I don't normally force a multi-gear downshift, never use remote start and don't let the vehicle idle to warm up. Most of the truck's life has been on the highway, and is probably much of the reason for the report. My curiosity piqued, I sent in the engine oil last week at its 5k mile oil change.

Here is the ATF Report. I'm happy! To continue the trend, I'll be keeping with drain-fills every 10-15k miles.

Edited October 25, 2022 by 16LT4

Eddie 70 · October 25, 2022

Been changing a gallon of fluid in my 2014 every 15k miles for the last several years. I use GM fluid because it is easy to get. The fluid looks new every time I check it now. I am currently at 120k miles and the truck seems to be doing fine. I agree with you that frequent changes helps. Blackstone seems to think it does.

steelerdude15 · October 27, 2022

I am also in this boat. I drained/refilled 3.5 quarts last weekend at 45,000 miles. I dropped the pan and changed the filter and six quarts at 30,000 miles. I plan on continuing to follow this schedule.

Grumpy Bear · October 27, 2022

I do an 8 quart Red Line D6 drop and fill every 25K. (aftermarket pan).

Ran a "pill flip" for years. Recently installed the new 70C thermostat and monitor temps like a hawk on spring rabbit.

As mine is behind a 4.3 I don't have the problematic V8 JMBX torque converter.

162K on the clock. Almost 3900 hours it now and it shifts flawlessly, hot or cold.

16LT4 · October 28, 2022

On 10/26/2022 at 10:02 PM, steelerdude15 said:

I am also in this boat. I drained/refilled 3.5 quarts last weekend at 45,000 miles. I dropped the pan and changed the filter and six quarts at 30,000 miles. I plan on continuing to follow this schedule.

Only 3.5 quarts? Every drain/fill I've ever performed on a 6L80 takes 6.5 quarts. Even a 6L45 will take 4.5-5 quarts.

steelerdude15 · October 29, 2022

13 hours ago, 16LT4 said:

Only 3.5 quarts? Every drain/fill I've ever performed on a 6L80 takes 6.5 quarts. Even a 6L45 will take 4.5-5 quarts.

I should have been more clear about what I did. I extracted 3.5 quarts out of the dipstick tube and put the same amount back in. I didn’t drop the pan this time around. I plan on dropping the pan at 60,000 miles.

swathdiver · October 29, 2022

Good report, here are two of mine for comparison. ACDelco Dexron VI only seems to last for about 40K miles.

16LT4 · November 2, 2022

On 10/29/2022 at 1:01 AM, steelerdude15 said:

I should have been more clear about what I did. I extracted 3.5 quarts out of the dipstick tube and put the same amount back in. I didn’t drop the pan this time around. I plan on dropping the pan at 60,000 miles.

Ah, OK. Shows how much "meat is left on the bone" sucking fluid out vs. a full drain. 3.5 quarts is only about 25% of the total fluid capacity. I was on the fence about pulling the pan to change the filter this time, but figured I'd wait for the UOA to come back. I'm glad I did; the filter can wait a while. For the next several 10s of thousands of miles, I'll simply remove the drain plug and let'er go. Pour in 6-6.5 quarts via the dipstick tube and drive away, couldn't be easier or quicker. Much easier than my BMW which has a fill hole requiring pumping in fluid with the engine running above me while watching fluid temps on the scan tool (filling temp is 50* C colder than operating temp on that one) or my wife's old VW which didn't have a fill hole, only a drain hole, requiring filling via the drain.