Diamond Reo Trucks, a historic American truck manufacturer, has produced a variety of durable and heavy-duty trucks for industrial, military, and commercial purposes.
Maintaining these trucks in optimal condition requires regular oil changes, and knowing the correct engine oil capacity is crucial for performance and engine longevity. In this post, we present a detailed Diamond Reo Engine Oil Capacity Chart covering the various models and engines associated with the brand.
Diamond Reo Engine Oil Capacity Chart
| Model | Year Range | Engine Type | Oil Capacity (Quarts) | Oil Capacity (Liters) | Recommended Oil Type |
|---|---|---|---|---|---|
| Diamond Reo Giant | 1967–1974 | Cummins NTC-335 | 38 | 36 | SAE 15W-40 |
| Diamond Reo C-116 | 1970–1975 | Detroit Diesel 8V71 | 36 | 34 | SAE 15W-40 |
| Diamond Reo Royale | 1971–1975 | Cummins VT-903 | 34 | 32 | SAE 15W-40 |
| Diamond Reo C-114 | 1967–1974 | Cummins NH-250 | 38 | 36 | SAE 15W-40 |
| Diamond Reo Raider | 1972–1975 | Caterpillar 3406B | 40 | 38 | SAE 15W-40 |
| Diamond Reo C-11664 | 1971–1975 | Detroit Diesel 6V92 | 30 | 28 | SAE 15W-40 |
| Diamond Reo Constructor | 1970–1979 | Detroit Diesel 12V71 | 44 | 42 | SAE 15W-40 |
| Diamond Reo 8800 | 1983–1995 | Cummins Big Cam III | 38 | 36 | SAE 15W-40 |
| Diamond Reo Conventional | 2003–2010 | Caterpillar C13 | 38 | 36 | SAE 15W-40 |
| Diamond Reo Dump | 1980–1995 | Cummins ISX | 40 | 38 | SAE 15W-40 |
| Diamond Reo Semi | 1970–1979 | Cummins KT450 | 48 | 45 | SAE 15W-40 |
| Diamond Reo Cabover | 1965–1975 | Cummins NH-220 | 36 | 34 | SAE 15W-40 |
| Diamond Reo Tandem Axle | 1970–1979 | Detroit Diesel 8V92 | 36 | 34 | SAE 15W-40 |
| Diamond Reo Long Hauler | 1980–1989 | Cummins NTC-400 | 40 | 38 | SAE 15W-40 |
| Diamond Reo Military M915 | 1978–1982 | Cummins NTC-400 | 40 | 38 | SAE 15W-40 |
| Diamond Reo C-119 | 1970–1979 | Caterpillar 1693 | 36 | 34 | SAE 15W-40 |
| Diamond Reo Short Haul | 1970–1979 | Detroit Diesel 6V71 | 30 | 28 | SAE 15W-40 |
| Diamond Reo Constructor II | 2005–2010 | Cummins ISM | 38 | 36 | SAE 15W-40 |
| Diamond Reo Mixer Truck | 1980–1995 | Cummins M11 | 36 | 34 | SAE 15W-40 |
| Diamond Reo Sleeper Cab | 1970–1979 | Cummins NTA-370 | 40 | 38 | SAE 15W-40 |
| Diamond Reo C-101 | 1968–1974 | Cummins N855 | 32 | 30.3 | SAE 15W-40 |
| Diamond Reo T-Line | 1970–1975 | Caterpillar 3408 | 42 | 39.7 | SAE 15W-40 |
| Diamond Reo DC-101 | 1961–1967 | Detroit Diesel 6V53 | 28 | 26.5 | SAE 15W-40 |
| Diamond Reo COE | 1965–1975 | Perkins 6.354 | 24 | 22.7 | SAE 15W-40 |
| Diamond Reo Heavy Duty | 1975–1985 | Detroit Diesel 6V92T | 32 | 30.3 | SAE 15W-40 |
Note: Oil capacities are approximate and may vary based on specific configurations. Always refer to the vehicle’s owner’s manual for precise specifications.
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Tips for Changing Oil in a Diamond Reo Truck
- Identify Your Engine First: Use the engine tag or owner’s manual to find the correct engine model.
- Warm Up the Engine: Warm oil drains better, carrying more contaminants with it.
- Drain Thoroughly: Let the oil drain completely before replacing the filter and adding new oil.
- Replace the Oil Filter: Always use a high-quality filter rated for your engine’s oil pressure.
- Refill Slowly and Check Level: Add oil in increments, checking the dipstick to avoid overfilling.
- Run and Recheck: After filling, start the engine for a few minutes, then shut it down and check oil levels again.
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Where to Get Diamond Reo Engine Specs
If you have a Diamond Reo truck and aren’t sure about its exact engine type, you can:
- Check the engine ID tag—usually located on the valve cover or engine block.
- Review the owner’s manual or service records.
- Contact vintage truck forums or groups specializing in Diamond Reo restorations.
- Use the VIN number to trace the original engine configuration (limited to newer Diamond Reo trucks post-2000s).
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Final Thoughts
Diamond Reo trucks are symbols of American trucking history, known for their strength and reliability. However, keeping them running depends heavily on correct maintenance practices, starting with the right engine oil capacity. Whether you’re restoring a classic Diamond Reo Giant or running a modern Reo dump truck, using this oil capacity chart will ensure your engine stays healthy and efficient.
