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Description
Lasting reliability ultimately comes down to one thing: consistent, proper maintenance. Using premium-quality oil and filters specifically engineered for your fluids and powertrain helps ensure long-term durability and can deliver hundreds of thousands of dependable, trouble-free miles.
Staying disciplined with factory-recommended service intervals and using the correct fluids is essential for preserving injector performance, supporting cooling system efficiency, and maximizing overall engine longevity, particularly in higher-mileage LLY trucks.
Factory Fluid Capacities & Recommended Weights
Engine Oil (6.6L Duramax)- Capacity: 10 quarts (with filter)
- Recommended Oil: 15W-40 diesel engine oil
- Cold Climate Option: 5W-40 synthetic
- Service Fill: 7.4 Quarts
- Total Capacity: 12.7 Quarts
- Recommended Fluid: Allison approved TES-668 or TES-295
- Capacity: 5.8 quarts
- Recommended Fluid: GM TranSynd Full Synthetic
- Capacity: 2 quarts
- Recommended Fluid: Dexron III ATF (Manual Shift) Auto-Trak II (AutoTrac)
- Capacity: 1.75 quarts
- Recommended Fluid: 75W-90 gear oil
- Capacity: 3.2–4.3 quarts ( Varies by model year)
- Recommended Fluid: SAE 75W-90
Proper filtration, paired with OEM-spec fluids, goes a long way toward protecting critical components like injectors, the turbocharger, and the transmission, while helping extend the overall life of your Duramax.