Shell Spirax S6 ATF A668 Synthetic Transmission Fluid, 1 Gallon

Shell Spirax S6 ATF A668 Full Synthetic Heavy-Duty Automatic Transmission Fluid

Shell Spirax S6 ATF A668 is a fully synthetic automatic transmission fluid specifically designed and approved for transmissions requiring Allison TES-668. Engineered for demanding commercial service, it delivers consistent shifting, dependable component protection, and extended fluid life—even under severe operating conditions.

Its advanced synthetic formulation helps maintain stable viscosity throughout the recommended service interval, protecting gears, bearings, and other transmission components while supporting efficient power transfer.

Key Features & Benefits

• Long-lasting transmission protection: Stable viscosity helps maintain the lubricating film needed to protect critical components under demanding loads.

• Extended service capability: Excellent oxidation resistance helps control deposits and supports longer fluid-change intervals where approved by the transmission manufacturer.

• Smooth, consistent shifting: Durable friction characteristics help maintain predictable shift quality and efficient power transfer.

• Cold-weather performance: Excellent low-temperature properties support effective transmission operation in cold conditions.

• Foam control and filterability: Helps maintain reliable lubrication and hydraulic control system performance.

• Mixed-fleet versatility: Suitable for qualifying Allison and certain Voith transmissions, along with selected applications calling for older DEXRON or MERCON specifications.

Recommended Applications

Designed for qualifying medium- and heavy-duty automatic transmissions used in commercial trucks, municipal fleets, school buses, coaches, emergency vehicles, vans, motorhomes, and heavy-duty pickups.

Backward compatible with Allison-approved TES-295, TES-389, and TES-468 fluids where recommended by Allison for on-highway applications.

Manufacturer Approvals

• Allison TES-668 — Approval 668-10222021

• DTFR 13C190

• DANA-OHTM-ATF-X — 22A-0004

• Voith H55.6335.xx

Suitable for Applications Requiring

• Volvo 97340 / 97341

• Ford MERCON

• GM DEXRON II / IIIG / IIIH

• MAN 339 Type V1

• JASO 1-A

• Caterpillar AT-1

Always follow the transmission manufacturer’s requirements for fluid selection, filter replacement, and service intervals.