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Ships within 48 hours · Estimated delivery Aug 16 - Aug 21
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Description
Mishimoto 2017+ GMC 6.6L Duramax L5P Transmission Thermal Bypass Valve KitThe Allison transmission is the backbone of your L5P Duramax. It's responsible for transmitting large quantities of torque from your V8 diesel powerplant. This torque generates a lot of heat, and if that heat isn't dissipated, it can destroy your transmission. The transmission cooler does a good job of keeping trans fluid temperatures in check, but only if the fluid can reach it. The stock cooling system of the Allison 1000 transmission utilizes an in
The Allison transmission is the backbone of your L5P Duramax. It's responsible for transmitting large quantities of torque from your V8 diesel powerplant. This torque generates a lot of heat, and if that heat isn't dissipated, it can destroy your transmission. The transmission cooler does a good job of keeping trans fluid temperatures in check, but only if the fluid can reach it. The stock cooling system of the Allison 1000 transmission utilizes an in-line thermal bypass valve that controls fluid flow to the transmission cooler. The purpose of this valve is to prevent transmission fluid from flowing to the cooler until it reaches operating temperature. The thermostat inside this valve is prone to failure, however, and when that happens, the fluid never flows to the cooler, and the transmission can overheat. That's why Mishimoto has developed a full-flow thermal bypass valve upgrade for your 2017+ Chevrolet/GMC 6.6L Duramax. Our CNC-machined aluminum full-flow thermal bypass valve not only looks better than the stock unit, but it performs better too. This Mishimoto thermal bypass valve eliminates the internal thermostat, providing full fluid flow to the transmission cooler in all running conditions. This setup is ideal for owners in warm climates, those performing heavy towing, and trucks needing the best possible cooling efficiency for their transmission. The Mishimoto thermal bypass valve features strategically machined internal passages, providing improved flow over the stock valve for more effective cooling. In addition, cooling fins machined into the valve body add even more heat dissipation. This 2017+ Chevrolet/GMC 6.6L Duramax L5P Full-Flow Thermal Bypass Valve Kit is built to last a lifetime with a durable black anodized finish and our Mishimoto Lifetime Warranty.This Part Fits:
| Year | Make | Model | Submodel |
|---|---|---|---|
| 2021 | Chevrolet | Silverado 2500 HD | Custom |
| 2017-2021 | Chevrolet | Silverado 2500 HD | High Country |
| 2017-2021 | Chevrolet | Silverado 2500 HD | LT |
| 2017-2021 | Chevrolet | Silverado 2500 HD | LTZ |
| 2017-2021 | Chevrolet | Silverado 2500 HD | WT |
| 2017-2021 | Chevrolet | Silverado 3500 HD | High Country |
| 2017-2021 | Chevrolet | Silverado 3500 HD | LT |
| 2017-2021 | Chevrolet | Silverado 3500 HD | LTZ |
| 2017-2021 | Chevrolet | Silverado 3500 HD | WT |
| 2020-2021 | GMC | Sierra 2500 HD | AT4 |
| 2017-2021 | GMC | Sierra 2500 HD | Base |
| 2017-2021 | GMC | Sierra 2500 HD | Denali |
| 2017-2021 | GMC | Sierra 2500 HD | SLE |
| 2017-2021 | GMC | Sierra 2500 HD | SLT |
| 2020-2021 | GMC | Sierra 3500 HD | AT4 |
| 2017-2021 | GMC | Sierra 3500 HD | Base |
| 2017-2021 | GMC | Sierra 3500 HD | Denali |
| 2017-2021 | GMC | Sierra 3500 HD | SLE |
| 2017-2021 | GMC | Sierra 3500 HD | SLT |
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.5 ★★★★★
Based on 9 reviews
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Product Reviews
★★★★★ 5
Daily Staple Sunscreen
Size: 3 Fl Oz (Pack of 1)
I’ve been really impressed with this sunscreen—it’s become a daily staple for my face and hands. The SPF 70 gives great peace of mind, especially with regular sun exposure, and it feels lightweight rather than heavy or greasy.
It absorbs quickly and doesn’t leave that thick white cast, which is a huge plus for everyday wear. On my face, it layers well under makeup without pilling, and on my hands, it doesn’t feel sticky or transfer onto everything I touch.
I also appreciate that it holds up well throughout the day without needing constant reapplication (unless I’m outside a lot). Overall, it’s a reliable, high-protection sunscreen that’s comfortable enough to use every day.
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Reviewed in the United States on April 28, 2026
★★★★★ 5
Works well when properly applied
Size: 3 Fl Oz (Pack of 1)
I try to always buy the highest SPF that I can find. This one fits the bill. If you apply it thoroughly all over and then reapply every few hours, you shouldn't get burned. I've worn it to the water park numerous times now. I have very sensitive skin, and it's given me no issues. I even put it on my face, just being careful not to get too close to my eye area. Once it absorbs into your skin, it doesn't feel too sticky like some other sunscreens can. Just be aware that it will leave a white residue on your bathing suit if you get it on there, but I've always been able to wash it out and that's a small price to pay for proper sun protection!
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Reviewed in the United States on April 9, 2026
★★★★★ 5
Excellent product.
Size: 3 Fl Oz (Pack of 1)
Excellent product. The sun is extremely strong where I live, and I've been using this for several days now; it lasts a very long time on the skin. However, if you have very sensitive skin, I wouldn't recommend using it on your face—in my case, it caused a breakout. But for the neck, body, and arms, it’s excellent. I highly recommend it, and it doesn't leave a bad feel on the skin or an unpleasant smell. If you use it in the water, it is recommended to reapply every hour and 20 minutes, otherwise you might get sunburned.
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Reviewed in the United States on May 23, 2026
★★★★★ 4
Solid sunscreen!
Size: 3 Fl Oz (Pack of 1), Size: 3 Fl Oz (Pack of 1)
I just started using this sunscreen about a week ago. It doesn’t feel heavy on the skin, but as someone with a dark complexion, it will leave a faint white-cast at first. Simply just tap it into your skin more!
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Reviewed in the United States on April 11, 2026
★★★★★ 5
Non-greasy and absorbs quickly
Size: 3 Fl Oz (Pack of 1)
I really like this sunscreen. It’s very lightweight and absorbs quickly without leaving a white cast or greasy feeling like other sunscreens. I use it every day and it feels very comfortable on the skin, even under makeup.
It provides great protection and doesn’t irritate my skin. The size is also convenient to carry in a bag. I definitely recommend it if you’re looking for something effective and lightweight.
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Reviewed in the United States on April 19, 2026
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