Superior 6L80 6L90 8L90 Sure Cool System Upgrade STL010 with Bypass Gasket

For my 2018 GMC SIERRA 6 SPEED TRANS.Absolutely a must for newer gmc pickups. For several years my truck on occasion would start shifting hard then go into limp mode with no power. I would need to disconnect the battery and wait 20 min to clear codes and get going again but typically it would reoccur soon after. Codes inducated a tcm ans ecm issue. On my last 600 mile trip it broke down 6x but I turned on my trans temp display on my driver info center and saw the trans was hitting between 280 and 288 degrees when the problem occured.I did some research and discoveted gm had put the wrong transmission thermostat in the thermostat block attached to the side of the trans on the drivers side. I purchased this bypass in desperation and found it pretty easy to install. Just 2 trans lines held in place with a single bracket and 2 bolts which also held the trans thermostat housing in place. Very little trans fluid leaked.The kit was easy to install with the only slight difficulty was getting the c-clip out. Good easy instructions.After reassembly I was amnazed that my trans rarely gets above 170 and many times never gets above 150 degrees! Thats 100 to 140 degrees lower.That was over a month ago and no banging, hard shifts or issues at all! Since the trans had got so hot I did do a trans service myself which is a pia but will save you several hundred dollars.Even if you aren't experiencing similar issues I would highly recommend buying this. I believe in the long term it will extend the life of your gm trans. Well worth the $50. Just wish I had got it several years ago!

Good purchase! This bypass to the transmission thermostat does exactly what it says. Bought a new/used truck (Sierra 1500), drove it home three hours from purchase point. Thermostat on the driver's display showed the average running temperature on the highway at 196 degrees. It seemed like the thermostat never opened as it should have. Replace the bypass a couple days later. Now, after having a transmission fluid flush and some "Shudder-Fix" (which also helps to reduce temperature), the truck's transmission is now running on the highway at about 129 - 136 degrees; a far cry from 196-198 degrees. Install was pretty easy. Glad I did it! Take your time to do the install correctly and you will be happy you did it.

Be careful and know what you're doing. Worked great on my truck but a buddy of mine installed incorrectly, shot his plug out and leaked all the fluid. Steps are simple but if you're not comfortable have someone install for you. Wish I was there to help him out on his install 😂

All silverados need this bypass, especially in the south. Easy to install, very little ATF lost just let it cool more than I did the ATF is HOT.

Cold days you’ll get a check engine light for transmission temp out of range. Too cold for too long.

This was easy to put on and it really works. I was amazed. Work perfect for my 2015 Silverado Z71 four-wheel drive 5.3

Why did you pick this product vs others?:Customer service is top notch. The gasket was missing, I called and it was here in two days. Install was a piece of cake and took about 30 minutes. I highly recommend

Great option for the 8l90 in my 16 Silverado however if your vehicle does not have a transmission cooler purchase one this part can only do so much.