STL010 6L80/90 2014 & Up Sure-Cool System

The STL010 Sure-Cool System is an innovative solution designed to ensure full-time cooler flow in 6L80/90 transmissions from 2014 and newer. By addressing common cooling issues, this system helps maintain optimal transmission temp, ensuring your vehicle operates efficiently under demanding conditions. Whether you’re towing heavy loads, driving in extreme climates, or upgrading for performance, the Sure-Cool System is a game-changer for preserving transmission health and longevity.

Traditional cooling systems can restrict flow, especially when operating under lower pressures, leading to elevated transmission temp and potential wear on critical components. The STL010 leverages advanced cooler bypass technologies to provide consistent cooling. By bypassing factory restrictions, it allows continuous flow through the transmission cooler, reducing temperature spikes and promoting uniform heat dissipation.

The benefits of the STL010 Sure-Cool System include improved cooling efficiency, significantly lower transmission temp, and enhanced durability for your transmission. Maintaining a lower and more stable operating temperature can prevent overheating, extend the life of your transmission fluid, and reduce wear on internal components.

Choose the STL010 Sure-Cool System for unmatched cooling performance backed by proven cooler bypass technologies. With full-time cooler flow, your transmission is better equipped to handle the toughest driving conditions, ensuring peak performance and long-term reliability. Upgrade to the STL010 today and experience the difference it makes for your 6L80/90 transmission.

• Full time cooler flow
• Built in safety bypass
• Immediate cooler fill
• Immediate accurate fluid level check without warm-up cycle
• Reduced average operating temperatures
• Increased ATF life
• Reduced risk of overheating
• Reduced risk of planetary damage

Frequently Asked Questions

What does the STL010 Sure-Cool System actually do, and why is it needed for 2014-up 6L80/90 transmissions?

The STL010 Sure-Cool System ensures full-time flow through the transmission cooler by bypassing the factory thermal bypass valve that restricts cooler flow until the fluid reaches a set temperature. This reduces heat spikes, helps keep operating temperatures lower under load (towing, heavy traffic, hot climates), and improves transmission fluid life. 

What are the benefits I’ll see if I install the Sure-Cool System?

Key benefits include:

• Full time cooler flow (no waiting for fluid to warm up before cooling begins)

• Built-in safety bypass (so in case of blockage or problems, flow isn’t completely cut off)

• Immediate cooler fill and accurate fluid level checks without needing to warm up the transmission (so easier maintenance)

• Reduced average operating temperature (often by ~20%), which leads to less wear, less risk of overheating, and increased life for both fluid and internal parts

How hard is it to install, and can I do it myself?

Installation is relatively straightforward for someone with basic mechanical skills. The kit installs into the existing cooler line block / bypass valve area. However, because transmission cooling and fluid level are critical, if you’re not comfortable working on the transmission or related components, having a professional install it can help avoid mistakes and ensure everything is sealed correctly.

Will installing the Sure-Cool System affect shift quality or other transmission behavior?

Generally, no negative effects are expected. In fact, operating at lower, more stable temperatures tends to improve the reliability of internal parts (seals, clutches, etc.). But because the factory bypass valve is there for a reason (to allow warm-up), you might notice slightly slower fluid warm-up time. Still, for most users, the trade-off is beneficial.

Is this system compatible with all GM 6L80/6L90/8L90 units, or only certain years/models?

It is built for 2014 and newer 6L80/6L90 transmissions as well as compatibility with some newer 8L90/8L80/90E units from 2016 onward. If in doubt, you should verify your transmission model/year before purchasing - contact us at info@circledtrans.com