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

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Doubeleive

Wes
Supporting Member
Joined
Nov 7, 2017
Posts
23,744
Reaction score
34,725
Location
Stockton, Ca.
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

Member
Joined
Jan 13, 2023
Posts
36
Reaction score
40
I wouldn't be concerned, but I would upgrade the thermal bypass. (From someone who just replaced their transmission at 122k).
 

fozzi58

Full Access Member
Joined
Jun 2, 2017
Posts
380
Reaction score
280
Location
North Jersey
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

Full Access Member
Joined
Jun 2, 2017
Posts
380
Reaction score
280
Location
North Jersey
driving like a race car in a 1500
gotcha, suddenly all makes sense, carry on

...ummm. Some of us do.
 

Doubeleive

Wes
Supporting Member
Joined
Nov 7, 2017
Posts
23,744
Reaction score
34,725
Location
Stockton, Ca.
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

Full Access Member
Joined
May 5, 2019
Posts
788
Reaction score
1,991
Location
Northside H-Town
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.
 
Last edited:

Forum statistics

Threads
129,276
Posts
1,813,210
Members
92,384
Latest member
rick9667
Top