6L80 Normal Temperature?

Appleboy84 · April 14, 2019

2013 Silverado, LT, Vortec 5.3L V8, 6 speed auto (I believe that it is the 6L80), EC, 2WD, HD Cooling, 69,XXX miles, transmission and ATF have never been touched.

I recently started looking at the transmission operating temperature of my truck. I have yet to see what the temperatures are in the summer times (summers where I live can get up to a 100F, last year it was mostly around 85-95F), so I've been testing between mid-winter and mid-spring of 2019. I noticed that around 20-50F, the transmission will be around 99-110F. And between 50-65F, the transmission will be around 110-120F. This is with no trailer or load in the bed, and is highway driving with light city driving. These temperatures always seemed low to me. According to the original window sticker, since the truck is an All-Star Edition, the truck has HD cooling. The brochure says that this package provides extra transmission cooling. And as I said before, the the transmission has never had any service done to it yet.

In the owner's manual where it talks about transmission fluid checks, at some point (I don't remember what it said exactly), it made it sound like the operating temperature should be at least 160F.

My question is, what has been the operating temperatures for your truck? What features does your truck have, how do you drive it, and where do you drive it that might affect the transmission temperature?

diyer2 · April 14, 2019

First if you're going by the DIC it could be wrong.

Second I see up to 215 when towing.

If yours is running that cool, great.

Heat is the enemy of motors, transmissions, electronics etc.

Time for a service on that trans IMO.

intheburbs · April 15, 2019

If I run mine (the 2500 Suburban) long enough to get up to "operating temperature," it usually ends up being about 100° over the outside temps. So in the winter, it's running around 120°-130°. In the summer, it's running 190°-200°. Towing is another matter, I've had it as high as 241° pulling up long grades in the Rockies with an 8600-lb trailer.

All that being said, GM designed these things for an operating temperature of 190°-200°. That's what they consider "normal operating parameters." So as the poster above said, be happy yours is running cooler. No real downside, other than you might not be cooking off any condensation/moisture in the system.

diyer2 · April 15, 2019

7 minutes ago, intheburbs said:

Towing is another matter, I've had it as high as 241° pulling up long grades in the Rockies with an 8600-lb trailer.

No big deal with proper maintenance IMO.

intheburbs · April 16, 2019

8 hours ago, diyer2 said:

No big deal with proper maintenance IMO.

Agree. I've logged over 20,000 miles on this truck towing heavy, including multiple trips over the Rockies and the Eisenhower tunnel. Truck is frighteningly all original with 190k on the clock. And I'll be dragging the behemoth trailer back out to Wyoming in June.

sefiroxx · April 17, 2019

Plenty of discussion on Cadillac forum for oil life. Life is mainly tied to temperature and exposure to elements. If the temp on tranny is kept low, like yours, it will let forever

Grumpy Bear · April 17, 2019

If you let it idle for around a half hour after being warmed up the transmission temperature will nearly reach water temperature. That will get you to your "Hot Check" temperature. FYI.

Different trucks with the 6L80E over the years have employed various cooling strategies so comparing one trucks 'average' temperature to another can be problematic.

Max tow and 2500's, to the best of my knowing, don't have thermostats and run cooler. Some 1500's with cooling in both the radiator and the upper part of the A/C condenser have stats, some don't.

Factory fluid is a Group III and while it will take a hair more heat than the other mineral oils the seals and clutch bonding are still subject to the limits they always have been. I'm never happy with temperature over 220 F.

Mine use to run on a hot day, no load 225 F if run for hours upon hours. I deleted the thermostat and now get temperatures like you do season by season. As long at it gets over the dew point for the day and a minimum of 100 F (40 C) I worry not about moisture or the computer or anything else.

Seal deterioration and clutch delamination isn't a 'hit 240 F and they go bye-bye' proposition. It's more like a boxer getting hit by a punch that isn't hard enough in one strike to knock him out but after several rounds the cumulative damage sets him on his fanny. The defense for this is routine fluid changes and GM knows this. 45,000 mile changes for heavy service. Stop and go in the city can be heavy service. IMHO. Mines cool as the other side of the pillow, I run good fluid and I still change it at minimum every 50K.

If you tow and run 220 F + and think you immune because you have some 'super fluid' and don't need a cooler and don't need to change your fluids...to me....that's like driving home drunk every night. Getting away with it, if you do, isn't proof it's a great idea, Not even sound thinking. IMHO of course.

For what it's worth