For an Allison 1000 Series on-highway transmission, Allison recommends a fluid approved to TES 668. TES 295 and TES 468 fluids are also listed as approved for the 1000 Series; Allison advises customers using either to consider TES 668 at their next service. Confirm that the exact product is on Allison’s current approved-fluid list and follow the service instructions for your vehicle.
Which transmission fluid is best for an Allison 1000?
Choose a product that is currently approved to Allison TES 668 for an Allison 1000 Series on-highway application. Allison calls TES 668 its newest fluid specification and recommends TES 668 approved fluids for the 1000 Series. The recommendation applies to the specification, not to a brand ranking: the approval list is the place to check whether a particular product qualifies.
Do not select fluid on the basis of a label such as “synthetic” or a general claim that it is compatible. Those descriptions do not establish Allison approval. Check the exact product name against Allison’s approved-fluid list before buying.
How TES 668 compares with TES 295, TES 468, and TES 389
| Specification | What Allison guidance establishes | What to do |
|---|---|---|
| TES 668 | Recommended for Allison 1000 Series on-highway products; identified by Allison as its newest specification. | Preferred choice when the exact fluid is currently listed as approved for your application. |
| TES 295 | Listed as approved for Allison 1000 Series on-highway products. Allison recommends that current users consider TES 668 at their next service. | An approved option; consider TES 668 when the next service is due. |
| TES 468 | Listed as approved for Allison 1000 Series on-highway products. Allison recommends that current users consider TES 668 at their next service. | An approved option; consider TES 668 when the next service is due. TES 468 and TES 295 should not be assumed to be identical. |
| TES 389 | Listed by Allison for traditional on-highway products. Allison’s service bulletin associates it with standard rather than extended change intervals. | Use only after confirming it applies to the specific transmission and vehicle; follow the matching service guidance. |
Allison’s approved-fluid guidance says it recommends TES 668 approved fluids to enhance performance and durability across operating environments. It separately advises customers using TES 295 or TES 468 to consider TES 668 for their next service. These recommendations do not establish a performance ranking among individual fluid brands.
#1 Best Overall
- 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.
How to determine the service interval
There is no single mileage interval that applies to every Allison 1000. Allison’s Fluid/Filter Change Recommendations bulletin #1099, Rev. BB, dated June 6, 2023, says the interval depends on transmission model, vocation or duty cycle, and fluid type. It associates TES 668 and TES 295 with extended change intervals, and TES 389 with standard change intervals.
Use the maintenance schedule for the exact vehicle and transmission, along with applicable service documentation. Operating conditions can affect maintenance needs, so do not apply an interval from a different vehicle, vocation, or fluid specification without confirming that it matches your setup.
Rank #2
- TranSynd is a full-synthetic, automatic transmission fluid designed specifically for ALLISON transmissions / TES 468 is now covered by TranSynd 668
- Allows for extended drain intervals of up to 300,000 miles / 48 months in general-duty transmissions and up to 150,000 miles / 48 months in severe-duty transmissions
- 12 times longer drain intervals than conventional and other non-TES 668 and non0-TES 295 fluids
- Shear stability that helps maintain a stable viscosity which provides wear protection in gears throughout the drain interval
- Improved gear protection, extended anti-shudder durability and extended clutch-friction durability
Fluid quantity and filter fitment depend on the service
A fluid-loss estimate for a control-main-filter change is not the same as total refill capacity. The quantity required can vary with vehicle year, pan and filter arrangement, transmission configuration, and the work being performed. Allison’s bulletin gives a control-main-filter fluid-loss estimate for 1000 and 2000 product-family transmissions, but it does not establish one universal refill quantity for every Allison 1000 service.
Likewise, there is no single filter part number established for every Allison 1000 application. Confirm the filter and fluid quantity against the exact vehicle and service procedure before purchasing parts or filling the transmission.
Quick Recap
Best Value
- Backward compatible with previous Dexron automatic transmission fluids and can be used as a much-improved replacement for older vehicles/transmissions originally using previous Dexron fluids
- Improved performance over previous Dexron fluids in: friction durability, viscosity stability, aeration and foam control, and oxidation resistance
- Potential to enable improved fuel economy and longer transmission life
- Provides for extended drain intervals. Provides consistent shift performance, even in extreme conditions.
Rank #4
- TranSynd is a full-synthetic, automatic transmission fluid designed specifically for ALLISON transmissions / TES 468 is now covered by TranSynd 668
- Allows for extended drain intervals of up to 300,000 miles / 48 months in general-duty transmissions and up to 150,000 miles / 48 months in severe-duty transmissions
- 12 times longer drain intervals than conventional and other non-TES 668 and non0-TES 295 fluids
- Shear stability that helps maintain a stable viscosity which provides wear protection in gears throughout the drain interval
- Improved gear protection, extended anti-shudder durability and extended clutch-friction durability
Rank #3
- 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.
Before buying fluid for an Allison 1000
- Identify the application. Confirm the vehicle, Allison 1000 configuration, and on-highway use that the service instructions cover.
- Check approval. Search Allison’s current approved-fluid list for the exact product and specification; do not rely on a generic compatibility claim.
- Match the maintenance schedule. Use the interval applicable to the transmission model, duty cycle, and fluid type, rather than a universal mileage figure.
- Verify service quantity and filter. Check the vehicle-specific procedure and fitment before ordering; filter-change fluid loss does not equal total refill capacity.
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