---
product_id: 321925241
title: "Stone River Products Castrol TranSynd 668 Allison 2021 Updated SPEC 1 GALLON ONLY BY DOXA WORLDWIDE"
brand: "castrol"
price: "19150 kr"
currency: ISK
in_stock: true
reviews_count: 13
category: "Castrol"
url: https://www.desertcart.is/products/321925241-stone-river-products-castrol-transynd-668-allison-2021-updated-spec
store_origin: IS
region: Iceland
---

# Thermal & oxidative stability Extended clutch-friction durability Improved gear protection Stone River Products Castrol TranSynd 668 Allison 2021 Updated SPEC 1 GALLON ONLY BY DOXA WORLDWIDE

**Brand:** castrol
**Price:** 19150 kr
**Availability:** ✅ In Stock

## Summary

> 🛠️ Drive with confidence, shift with precision — the pro’s choice in transmission fluid!

## Quick Answers

- **What is this?** Stone River Products Castrol TranSynd 668 Allison 2021 Updated SPEC 1 GALLON ONLY BY DOXA WORLDWIDE by castrol
- **How much does it cost?** 19150 kr with free shipping
- **Is it available?** Yes, in stock and ready to ship
- **Where can I buy it?** [www.desertcart.is](https://www.desertcart.is/products/321925241-stone-river-products-castrol-transynd-668-allison-2021-updated-spec)

## Best For

- castrol enthusiasts

## Why This Product

- Trusted castrol brand quality
- Free international shipping included
- Worldwide delivery with tracking
- 15-day hassle-free returns

## Key Features

- • **Unmatched Gear Defense:** Protect your transmission with industry-leading gear durability.
- • **Stay Cool Under Pressure:** Superior thermal stability prevents oil thickening and deposits.
- • **Smooth Shifts, Every Time:** Experience extended anti-shudder performance for flawless driving.
- • **Corrosion? Not on Our Watch:** Advanced formula resists corrosion and foaming for long-lasting reliability.
- • **Universal Fit, Professional Grade:** Engineered to meet Allison 2021 specs, perfect for diverse vehicle needs.

## Overview

Stone River Products Castrol TranSynd 668 Allison 2021 Updated SPEC is a premium synthetic transmission fluid designed for superior gear protection, extended clutch and anti-shudder durability, and excellent resistance to corrosion and foaming. Engineered to meet the latest Allison 2021 specifications, this 1-gallon universal fit fluid ensures optimal thermal and oxidative stability, preventing deposits and oil thickening for enhanced transmission performance.

## Description

Buy Stone River Products Castrol TranSynd 668 Allison 2021 Updated SPEC 1 GALLON ONLY BY DOXA WORLDWIDE: Fuel Additives - desertcart.com ✓ FREE DELIVERY possible on eligible purchases

Review: Great for the Allison - Great fluid. Chevy shifting so much better now.
Review: Transynd 668 - Top notch fluid!! Thanks

## Features

- Delivers improved gear protection.
- Delivers extended anti-shudder durability.
- Delivers extended clutch-friction durability.
- Excellent corrosion and foaming resistance.
- Excellent thermal and oxidative stability that helps to prevent deposits and oil thickening.
- Fit type: Universal

## Technical Specifications

| Specification | Value |
|---------------|-------|
| ASIN | B095SZB2DK |
| Best Sellers Rank | #3,211 in Automotive ( See Top 100 in Automotive ) #16 in Transmission Fluids |
| Brand | Castrol |
| Customer Reviews | 4.9 4.9 out of 5 stars (967) |
| Date First Available | May 25, 2021 |
| Item Form | Liquid |
| Item Weight | 7.5 pounds |
| Liquid Volume | 1 Gallons |
| Manufacturer Part Number | TES 668 |
| Material | Synthetic |
| Number of Items | 1 |
| Package Dimensions | 10.83 x 8.15 x 4.37 inches |
| Package Information | Bottle |
| Recommended Uses For Product | Automotive |
| UPC | 079191219164 |
| Unit Count | 128.0 Fluid Ounces |

## Product Details

- **Brand:** Castrol
- **Item Weight:** 3.41 Kilograms
- **Liquid Volume:** 1 Gallons
- **Material:** Synthetic
- **Package Information:** Bottle

## Images

![Stone River Products Castrol TranSynd 668 Allison 2021 Updated SPEC 1 GALLON ONLY BY DOXA WORLDWIDE - Image 1](https://m.media-amazon.com/images/I/71RP2LrvVRL.jpg)
![Stone River Products Castrol TranSynd 668 Allison 2021 Updated SPEC 1 GALLON ONLY BY DOXA WORLDWIDE - Image 2](https://m.media-amazon.com/images/I/510jQvr1cIS.jpg)
![Stone River Products Castrol TranSynd 668 Allison 2021 Updated SPEC 1 GALLON ONLY BY DOXA WORLDWIDE - Image 3](https://m.media-amazon.com/images/I/51fS+M5Xa4S.jpg)
![Stone River Products Castrol TranSynd 668 Allison 2021 Updated SPEC 1 GALLON ONLY BY DOXA WORLDWIDE - Image 4](https://m.media-amazon.com/images/I/51ZQ2Q2uaES.jpg)

## Available Options

This product comes in different **Number Of Items** options.

## Questions & Answers

**Q: Can I use this in my 2001 silverado 2500hd with an allison transmission?**
A: Yes, I recommend flushing and filter (Both) try to remove as much of the Dino oil as possible.
Transcend works wonderfully in my '01 and '05 Chev Allisons

**Q: Can this be use with nissan rogue 2017?**
A: no

**Q: Ok for Genesis 80 2017**
A: no

**Q: I am trying to find the color of the fluid. Not able to find it on the product description. Any comments?**
A: It's red. Just like the older version.

## Customer Reviews

### ⭐⭐⭐⭐⭐ Great for the Allison
*by J***N on January 7, 2026*

Great fluid. Chevy shifting so much better now.

### ⭐⭐⭐⭐⭐ Transynd 668
*by K***N on February 1, 2026*

Top notch fluid!! Thanks

### ⭐⭐⭐⭐⭐ Only fluid to use in any Allison transmission
*by M***5 on February 26, 2026*

Started using Tes fluids 8 years ago in my 2005 duramax. Trans developed a shudder and jerking motion going downhill in cruise control. Called Allison tech support. Was told Dex VI wasn't good enough to protect 1000 series trans internals and seals. Changed to Tes 295 and all trans symptoms disappeared. Did forward system flush to get all Dex VI out of the system. 4 gal. Now I'm using 668. 322,000 mi and the trans shifts like new. Can be used in NP and Magna 263 and 261 transfer cases . I do a pan drain every 2 years and canister filter every 12 mo. The cleaner the fluid the cooler it runs.

## Frequently Bought Together

- Stone River Products Castrol TranSynd 668 Allison 2021 Updated SPEC 1 GALLON ONLY BY DOXA WORLDWIDE
- Allison 29539579 Screw-on Filter with Magnet Filter Kit replacing filter for Allison transmission per OEM Specs, For utility terrain vehicles
- ACDelco GM Original Equipment PF2232 Engine Oil Filter

---

## Why Shop on Desertcart?

- 🛒 **Trusted by 1.3+ Million Shoppers** — Serving international shoppers since 2016
- 🌍 **Shop Globally** — Access 737+ million products across 21 categories
- 💰 **No Hidden Fees** — All customs, duties, and taxes included in the price
- 🔄 **15-Day Free Returns** — Hassle-free returns (30 days for PRO members)
- 🔒 **Secure Payments** — Trusted payment options with buyer protection
- ⭐ **TrustPilot Rated 4.5/5** — Based on 8,000+ happy customer reviews

**Shop now:** [https://www.desertcart.is/products/321925241-stone-river-products-castrol-transynd-668-allison-2021-updated-spec](https://www.desertcart.is/products/321925241-stone-river-products-castrol-transynd-668-allison-2021-updated-spec)

---

*Product available on Desertcart Iceland*
*Store origin: IS*
*Last updated: 2026-03-07*