If I never replaced the transmission Thermal Bypass Valve, should I be running to the dealer ASAP?

[TahoeFL2017]

2017 Tahoe LT, 6 speed, never replaced this as far as I know - should I be concerned?

I don't tow, and Florida is pretty flat, so not a whole lot of stress ln my trans.

 

[Doubeleive]

2017 Tahoe LT, 6 speed, never replaced this as far as I know - should I be concerned?

I don't tow, and Florida is pretty flat, so not a whole lot of stress ln my trans.

if there are no issue's then no but it's something that could be done to perhaps help in the long run.
good maintenance is helpful, don't take it for granted that the transmission fluid will be good for 100k per the owners manual. that's a farce.

 

[TahoeFL2017]

I had all fluids changed at around 50k miles, so 30k on what's in there now.

Appreciate the reply though, i want to keep this truck long term so do whatever i can.

 

[Doubeleive]

I had all fluids changed at around 50k miles, so 30k on what's in there now.

Appreciate the reply though, i want to keep this truck long term so do whatever i can.

With the exception of the front & rear differentials I do all fluids annually and the diff's every other year. so coolant, brake, trans. the k2's are electric steering so nothing to do there. I also throw in some injector cleaner at least every 3 months and keep the throttle body and maf clean about the same although those can probably go a bit longer maybe 6 months to a year it can depend on how dirty the environment is that you frequent. for instance dirt roads are terrible for the intake and so more frequent cleaning should be done.

 

[steiny93]

I do all fluids annually and the diff's every other year.

What rational would anyone have for doing this? Why would anyone waste the dollars or the time?

 

[NickTransmissions]

What rational would anyone have for doing this? Why would anyone waste the dollars or the time?

Major heavy duty use (lots of towing/hauling). I recommend annual trans fluid changes for older units running Dex3 in HD applications but for daily driving/stock level usage I recommend once every 30-34k for transmission fluid and perhaps every 50-70k or so for the diff(s), regardless of fluid type used (you have a little more leeway with synthetic) but intervals should never be like 100k or more between changes, IMO.

 

[Doubeleive]

What rational would anyone have for doing this? Why would anyone waste the dollars or the time?

lol, because I follow a severe duty cycle and I tend to keep my vehicles for a long time, I don't drive it until breaks and never maintain it then and then dump it on some poor soul that now has to go spend a ton of money fixing stuff that should have been done already.
also i drive like the wife's water just broke and it's time

 

[steiny93]

lol, because I follow a severe duty cycle and I tend to keep my vehicles for a long time, I don't drive it until breaks and never maintain it then and then dump it on some poor soul that now has to go spend a ton of money fixing stuff that should have been done already.
also i drive like the wife's water just broke and it's time

my rational:
1) you aren't doing anything 'severe' with your 1500; no plow, no commercial work, it isn't severe
Here is how GM describes severe: Extreme service. For vehicles mainly driven off road in four wheel drive or used in farming, mining, forestry, Department of Natural Resources (DNR), or snow plowing.
2) high frequency fluid change doesn't equate to long life; driving style matters, dumping still in spec fluid doesn't do anything magical
3) unless you are piling a ton of miles, annual is beyond even the severe schedule, per GMC's: oil @ 7500, trans & transfer @ 45k, cooling @ 150k, the severe schedule doesn't even list brake fluid

If it makes folks feel better, by all means dump the fluids every week.
But the reality is that changing fluids matters near zero if you are close to manufacturer recommended. If you disagree go dig around fleet maintenance schedules for light duty vehicles within fleets that run out to say 250k (don't look at 100k fleets, to short of a duty cycle, anything will get to 100k). Those fleets are incented to minimize major break issues within the service cycle of the vehicles, they are zeroed in on maintenance to get there and they have the data to back it up.

 

[Doubeleive]

my rational:
1) you aren't doing anything 'severe' with your 1500; no plow, no commercial work, it isn't severe
Here is how GM describes severe: Extreme service. For vehicles mainly driven off road in four wheel drive or used in farming, mining, forestry, Department of Natural Resources (DNR), or snow plowing.
2) high frequency fluid change doesn't equate to long life; driving style matters, dumping still in spec fluid doesn't do anything magical
3) unless you are piling a ton of miles, annual is beyond even the severe schedule, per GMC's: oil @ 7500, trans & transfer @ 45k, cooling @ 150k, the severe schedule doesn't even list brake fluid

If it makes folks feel better, by all means dump the fluids every week.
But the reality is that changing fluids matters near zero if you are close to manufacturer recommended. If you disagree go dig around fleet maintenance schedules for light duty vehicles within fleets that run out to say 250k (don't look at 100k fleets, to short of a duty cycle, anything will get to 100k). Those fleets are incented to minimize major break issues within the service cycle of the vehicles, they are zeroed in on maintenance to get there and they have the data to back it up.

driving it like a race car is not mentioned anywhere?
at what temp does the brake fluid begin to break down?
I will tell you 400-600 deg. If you think I don't get my brakes that hot just driving somewhat adventurously then you are mistaken
I can get them heated up pretty good just going a mile or 2 down the road.
you have to keep in mind GM wants to you to break down (eventually) that's how they stay in business, which is why parts have a rated life expectancy.
if you don't think that driving a vehicle vigorously is considered severe then you are sadly mistaken
even the transmission shop that built my transmission requires me to have the fluid changed annually to maintain my warranty, because they know better.
and I change my oil every 3k lol (god forbid)
in all reality I drive my vehicle harder than any of those industries you mentioned.
severe duty does not have to be "by the book" definition

 

[steiny93]

driving it like a race car is not mentioned anywhere?
at what temp does the brake fluid begin to break down?
I will tell you 400-600 deg. If you think I don't get my brakes that hot just driving somewhat adventurously then you are mistaken
I can get them heated up pretty good just going a mile or 2 down the road.
you have to keep in mind GM wants to you to break down (eventually) that's how they stay in business, which is why parts have a rated life expectancy.
if you don't think that driving a vehicle vigorously is considered severe then you are sadly mistaken
even the transmission shop that built my transmission requires me to have the fluid changed annually to maintain my warranty, because they know better.
and I change my oil every 3k lol (god forbid)
in all reality I drive my vehicle harder than any of those industries you mentioned.
severe duty does not have to be "by the book" definition

driving like a race car in a 1500
gotcha, suddenly all makes sense, carry on

 

[Doubeleive]

driving like a race car in a 1500
gotcha, suddenly all makes sense, carry on

all those service intervals in the book are pretty baseline, like driving it to church on Sunday at 55mph
the more you push the pedals the more wear & tear and therefore more frequent intervals should be performed.
am I waisting my money on more frequent service? perhaps but I would rather be safe than sorry
doing it more frequent also allows me to monitor the condition, metal shavings, etc are a indication that something is wrong.
I don't just drive it until it leaves me on the side of the road wondering what happened.
I don't just change the fluids I get under it and look for signs of wear and leaks, overall condition, pop the hood take a look at stuff make sure a wire isn't rubbing on a sharp edge or anything of that nature.
it's called maintenance and preventative maintenance. I put injector cleaner in, I clean the air filter and intake and throttle body, inspect my brakes, inspect the suspension.
I learned my lesson a LONG time ago

 

[gapost]

I wouldn't be concerned, but I would upgrade the thermal bypass. (From someone who just replaced their transmission at 122k).

 

[fozzi58]

2017 Tahoe LT, 6 speed, never replaced this as far as I know - should I be concerned?

I don't tow, and Florida is pretty flat, so not a whole lot of stress ln my trans.

I have done my trans fluid about every 25k, give or take. I also had the thermal bypass done when I put the Whipple on my truck (along with the upgraded trans lines). That was at 62k. I'm almost at 100k and still not a single speck of metal in the trans fluid (changes at 81k). However, changing the torque converter is probably part of the reason why my trans is still rock solid even with the "performance abuse".

The 6L80 has a know issue with the torque converters from GM. Even when they bulletin the converter, it can still have issues. There are multiple mechanics on youtube and tiktok that discuss the shudder in the 6L80/90 & 8L80/90 and its related to the converter and the factory tune. While you don't need a 3000rpm stall converter, if you want to get 250k out of that trans without replacing it, I would recommend getting a better stall from a company like Yank, Circle D, etc. If you go this route - CALL THEM and discuss with them what you use the truck for. Don't just go online and order something.

50k mile fluid changes are probably fine for the driving you are doing. Also - oil change every 3000k miles. @Doubeleive is probably the exception to the maintenance rule, and while his suggestions do have some validity, more than likely it's overkill for you. That being said, I should probably be following his suggestions since I treat my Burb like a 9 passenger Vette.

 

[fozzi58]

driving like a race car in a 1500
gotcha, suddenly all makes sense, carry on

Autocross in a 'Burb

Just wanted to tell everyone about my experience. Friday I took the Suburban to Autocross school at the Meadowlands (MetLife Stadium). Obviously I was a true oddball since most of the cars were meant or built for this type of driving. Surrounded by Miatas, BMWs, Vettes, and a few Stangs...

www.tahoeyukonforum.com

...ummm. Some of us do.

 

[Doubeleive]

I have done my trans fluid about every 25k, give or take. I also had the thermal bypass done when I put the Whipple on my truck (along with the upgraded trans lines). That was at 62k. I'm almost at 100k and still not a single speck of metal in the trans fluid (changes at 81k). However, changing the torque converter is probably part of the reason why my trans is still rock solid even with the "performance abuse".

The 6L80 has a know issue with the torque converters from GM. Even when they bulletin the converter, it can still have issues. There are multiple mechanics on youtube and tiktok that discuss the shudder in the 6L80/90 & 8L80/90 and its related to the converter and the factory tune. While you don't need a 3000rpm stall converter, if you want to get 250k out of that trans without replacing it, I would recommend getting a better stall from a company like Yank, Circle D, etc. If you go this route - CALL THEM and discuss with them what you use the truck for. Don't just go online and order something.

50k mile fluid changes are probably fine for the driving you are doing. Also - oil change every 3000k miles. @Doubeleive is probably the exception to the maintenance rule, and while his suggestions do have some validity, more than likely it's overkill for you. That being said, I should probably be following his suggestions since I treat my Burb like a 9 passenger Vette.

Lol that's a good analogy a nine person Vette for sure.

 

[Bigkevschopshop]

I will say the bypass valve reprogram Superior stl010 has been great. My trans feels so much better towing and driving around normally, and engaging vette mode here and there its been alot more happy with a nice exhaust pop on shifts. I probably need to update the TC but its been doing fine and no signs of slippage at all, just a clunky shift in 2-3 every once in a while at light throttle. The TC destruction normally takes the rest of the trans with it, and its a heat issue also, hence why they did a TSB on the cooler bypass. Then folks ask, how hot is too hot... Well trans fluid isn't engine oil, and its a hydraulic fluid. Anything over 200 degrees is bad for transmission fluid. Cooler the better when it comes to transmissions for me.

Before the valve reprogram towing or empty I was in the 190s all the time even with the updated cooler bypass.
After I am in the 155 area with no trailer, and with trailer and load, 170-172. And this is in 90 degree weather here.

An upgraded TC will see the 6l80e outlive most counterparts. And I agree, service should be approached to how you drive it and use it.

Tow alot, run it on the severe duty schedule, drive it hard, same thing. (Applicable for Doubeleive)

Cruise around like a soccer mom, then go standard schedule. (Not applicable for Doubeleive )

Service is the most overlooked part of these rigs for the standard owner, I believe that most of us here are a bit more up on the service and don't let things slide.