6L80 6L90 8L90 Sure Cool System Upgrade STL010

I rarely leave reviews for items. But this one is a must have. My Silverado with 72k miles left me stranded in the middle of the dessert with an overheated transmission. After searching for answers on Google, I came across this little gem. Took 10-15 minutes to install and it solved the issue. Now, my transmission runs much cooler. Highly recommend this product.

A friend recommended this upgrade to me, but I was hesitant. Me mess with my transmission? I don't think so. But, after I watched several videos I took the plunge. Item is obviously well manufactured. High-quality parts. Instructions were clear as well. Took me about 45 minutes with a couple of wrenches, and I went slow. Toughest part was realigning the clips on the fluid lines when reassembling. My Silverado has a transmission temperature gauge, so I could measure real-world results. What previously was 196 degrees, is now 145 degrees. Huge difference. Highly recommend.

This product works as described, and is fairly easy to install following numerous videos that are available online. I was also changing my transmission filter and fluid at the same time, but as a guess, if I were to just install this bypass it would probably be about a 15 minute job. The hardest part of the whole job is getting the snap ring out of the housing as mine was a bit dirty/somewhat corroded and stuck. A couple blasts of brake or carb cleaner and some compressed air helped. All-in-all, not really any gotchas with this job other than to make sure to clean everything and that the o-rings stay on the cooler lines. I also purchased a replacement gasket, just in case, but the factory gasket was fine and I just reused it.As far as function goes, this product does what it says. Prior to installing on my 2020 Yukon, the transmission temp would quickly climb to 195°. Now, it generally runs much cooler, and maxes out at <150°.This so far has been a great mod, and is worth the price and minor effort to install.

I was running 200-220F hot summer temps (Florida) when I bought my 2018 5.3L Suburban high-mileage used in 2021. I did see a reduction into typical 190s temps, maybe breaking 200 on hot days with a lot of shifting, after doing a fluid evac and replacement. But this device is the REAL DEAL that dropped my temps. I can't get the thing to go over 170F NO MATTER WHAT I DO.Now, because the fluid is running through the cooler CONSTANTLY, it only gets anywhere above 155F if I'm sitting in traffic on a hot day and moving slowly without much air reaching the trans cooler. But as soon as I'm back up to speed, especially highway speeds, the temps start dropping and it's not unusual to cruise at just below 150F on the highway with good air flow.I am 100% certain I have just saved, or at least prolonged, the life of my torque converter. If you have a 6L80 this is as important a thing as you can do for it, and it only takes half an hour with extremely basic tools. Most complicated thing you need is snap-ring pliers that squeeze together (not the one that expands).This is every bit as important with these trucks as an AFM disabler to preserve your lifters, and, frankly, this is a more certain fix than the AFM disabler offers. GM has acknowledged that 190-220F is way too hot for your torque converter in a TSB release, but their "fix" is another thermostat that can freeze shut. This fix allows flow even if everything inside the device fails - the default is open flow to the cooler and worst case, in very cold climate in winter, you might need an extra couple minutes of morning warmup. In most of the country, you just leave it so that it's always open - the check-ball lets it clear out any overpressure from one side or the other so there's no harm that can occur.Just a BRILLIANT solution!!!BTW, my PHOTO shows the HIGHEST TEMP I have been able to reach since installing, and driving in warm weather - average daytime outdoor temp here is 80F. To get it up to 169F as shown in photo I had to run it at high revs in 1st gear in stop-and-go city traffic on a blistering day. That's the max I can get it up to now, and it takes a lot of trying! As soon as I hit the highway, or just 45mph in the city, that temp backs down into the 150s quickly.

This could save you a $4000+ transmission replacement! For the money this product is an amazing deal. Fit great into the factory transmission TXV body. Factory TXV was a bit difficult to remove but after that it was smooth sailing. I included before and after pictures of my transmission temps with very spirited driving. My vehicle has a heavily modified engine paired to an otherwise stock 6L80 with a 3400-3600 triple disc billet torque converter.

Must Need! Transmission much cooler! Easy install! Well worth the money!

It works plain and simple. My transmission was running at 195* daily. I installed this bypass and ran my truck all day. It never went above 160*. That included city stop and go, idling and highway driving. It was very easy to install and it only took me 20-25 minutes. I lost very little fluid during the process.

Great value for the money, could save your transmission. Fits housing as intended. Dropped my normal temp by about 40 degrees.