LMM Duramax Fluid Capacity Guide (2007.5–2010) | Merchant Automotive
Engine Coolant
Capacity: 20.3 qt (auto) / 20.7 qt (manual)
Type: Dex‑Cool 50/50 premix
Service Interval: Replace every 5 years or 100,000 miles (initial), then every 2–3 years thereafter.
Transmission – Allison 1000 (6‑speed)
Pan & filter change: 7.4 qt / Total capacity: 12.7 qt
Fluid: Dexron VI / Transynd
Service Interval: Spin-on filter every 15,000 miles; full fluid service every 50,000 miles under severe use.
Shop Deep Pan & Filter Kit
Front & Rear Differentials
Front capacity: 1.8 qt; Rear capacity: 3.8 qt
Fluid: 75W‑90 synthetic (GL‑5)
Service Interval: Replace every 50,000 miles under normal use, or 30,000 under towing or heavy load.
Power Steering
Capacity: ~2 qt
Fluid: GM Power Steering Fluid or Dexron III/VI ATF
Service Interval: Inspect every 15,000 miles; flush every 50,000 miles.
Brake Fluid
Capacity: 1–2 qt for full flush
Fluid: DOT 3 or DOT 4
Service Interval: Every 2–3 years under normal use, or every 50,000 miles in severe-duty conditions.
Note: DOT 4 is fully compatible with DOT 3 and may be used for the LMM platform, especially in towing or high-heat conditions. It provides higher boiling points and improved performance under heavy braking.