Engine comparison
Detroit DD13 vs DD15: Specs, Weight and Oil Capacity Compared
The Detroit DD13 and DD15 are two different engines. The DD13 is 12.8 liters and the DD15 is 14.8 liters. Detroit lists the DD13 at 370–525 hp and the DD15 family at 425–505 hp. On the sheets we read, the DD13 is lighter and holds 40 qt of oil against 45. We could only find the DD13 weight and oil fill on Detroit's Australia and New Zealand sheets. Detroit's North American DD13 oil table was not available to us. There is no spec-sheet winner.
Figures for DD13 vs DD15 are taken from the manufacturers' own published documents. Last reviewed November 3, 2026.
DD13 vs DD15: side-by-side specs
| Spec | Detroit DD13 | Detroit DD15 |
|---|---|---|
| Displacement | 12.8 L | 14.8 L (906 cu in) |
| Configuration | Inline 6-cylinder | Inline 6-cylinder |
| Power range | 370–525 hp (Gen 5) | 425–505 hp (DD15 family) |
| Torque range | 1,250–1,850 lb-ft (Gen 5) | 1,550–1,850 lb-ft |
| Bore × stroke | 5.20 in × 6.15 in (132 mm × 156 mm), Australia/NZ sheet | 5.47 in × 6.42 in (139 mm × 163 mm) |
| Compression ratio | 20.3:1, Australia/NZ Gen 5 sheet | 21.0:1 |
| Dry weight | 2,447 lb (1,110 kg), Australia/NZ Gen 5 sheet | 2,718 lb (1,233 kg) |
| Oil and filter service fill | 40 qt (38 L), Australia/NZ sheets | 45 qt (43 L) |
| Oil interval | Not read: North American table not available | 35,000–75,000 mi by duty cycle |
| Published design life (B10) | Not stated | Not stated on the Gen 5 spec sheet |
| Major-component warranty as printed by the maker | Not stated on the pages we read | Months 25–60 or 500,000 mi, parts only (no labor) |
| Available in the Freightliner Cascadia | Yes | Yes |
Full detail for each engine: Detroit DD13 guide and Detroit DD15 guide.
What actually decides DD13 vs DD15?
We don't name a winner in DD13 vs DD15: there's no independent, like-for-like study of fuel economy or reliability for these engines. These are the facts that decide it for a given truck and duty cycle.
- Rating, not displacement, sets the power
- Detroit's lists put the DD13 as high as 525 hp and the DD15 family as high as 505 hp. The DD15 starts higher, at 425 hp against 370. So a DD13 is not automatically the weaker engine. Compare the exact rating on each truck, not the liter count.
- Weight and payload
- On the sheets we read, the DD13 is about 270 lb lighter (2,447 lb against 2,718 lb). The DD13 figure comes from Detroit's sheet for Australia and New Zealand, so treat it as an indication. Whether that matters depends on how close your trailer is to the weight limit.
- Get the oil interval and warranty in writing
- We have Detroit's full oil table for the DD15 and not for the DD13 in North America. Do not assume the DD13 uses the DD15 numbers. Ask for the DD13 interval and warranty terms for the specific truck, in writing.
- Where each one is sold
- Both are offered in the Freightliner Cascadia, and the DT12 transmission is listed with both. Detroit also lists the DD13 in the M2 112 Plus, the 114SD Plus and the Western Star 47X and 49X.
Put your DD13 vs DD15 service interval on a schedule with the maintenance scheduler. Decode warning lights with the fault code lookup. Before you buy a used truck, run the VIN decoder and used truck inspection checklist.
More engine comparisons and guides
Frequently Asked Questions
Is the DD13 better than the DD15?+
Neither Detroit page we read states a design life, and there is no independent reliability or fuel-economy study. So there is no honest way to name a winner. The DD13 is smaller and lighter on the sheets we read. The DD15 is larger. The right one depends on the rating you need and the weight you pull.
What is the difference between the DD13 and the DD15?+
Size is the main difference. The DD13 is 12.8 liters and the DD15 is 14.8 liters. The bore and stroke are different too. The DD13 holds 40 qt of oil on Detroit's Australia and New Zealand sheets, and the DD15 holds 45 qt on its North American sheet.
Which has more horsepower, the DD13 or the DD15?+
It depends on the rating. Detroit lists the DD13 from 370 to 525 hp and the DD15 family from 425 to 505 hp. The DD13's top rating is higher than the DD15's top rating on those lists.
How much oil does each one take?+
Detroit lists 40 quarts (38 liters) for the DD13 on its Australia and New Zealand sheets. It lists 45 quarts (43 liters) for the DD15 on its Gen 5 North American sheet. Check your operator's manual before you buy oil.
Sources
- Detroit DD13 Gen 5 engine page (demanddetroit.com)
- Detroit DD13 Gen 5 technical specifications, Australia and New Zealand
- Detroit DD13 technical specifications, Australia (earlier version, same 40 qt fill)
- Detroit DD15 Gen 5 On-Highway Technical Specs (Detroit / DTNA)
- Detroit DD15 engine page (demanddetroit.com)
Choosing between DD13 vs DD15? Let a dispatcher help.
Grow Trucking finds loads, negotiates rates and does the paperwork for owner-operators and small fleets. Tell us what you haul and we will show you how a DD13 vs DD15 truck fits the lanes we book.
Also: About Grow Trucking · Refer a carrier · Trucking blog
Specs, intervals and warranty terms for the DD13 vs DD15 engines change by model year and configuration. Power and torque ranges are from our engine reference. Confirm exact figures for a specific truck against the manufacturer's current documentation and your written warranty before buying or setting a service schedule.
Free tools for a DD13 vs DD15 decision
Decode fault codes for the DD13 vs DD15 engines, keep service on schedule and check a truck before you buy.
- Diesel Fault Code Lookup (SPN/FMI)Decode the SPN/FMI fault codes either DD13 vs DD15 engine reports.
- Preventive Maintenance SchedulerTrack oil and filter intervals for a DD13 vs DD15 truck by odometer and duty cycle.
- Breakdown Cost EstimatorEstimate what a breakdown costs in repairs and lost revenue on a DD13 vs DD15 truck.
- Truck Breakdown TriageIf a DD13 vs DD15 engine shows a red lamp or overheats, see if you should stop now.