AMSOIL MAX-DUTY vs MOBIL DELVAC 1 ESP
Both full-synthetic CK-4 oils with strong OEM coverage. The difference is in wear data, drain intervals, and FA-4 availability.
AMSOIL Max-Duty vs Mobil Delvac 1 ESP
Both are full synthetic CK-4 oils in 15W-40 with broad OEM coverage. The data tells a different story on wear and extended drain.
AMSOIL Signature Series Max-Duty 15W-40 (DME)
Full synthetic PAO/ester. Dual-rated CK-4 and FA-4. Tested at 6× the wear protection of the industry standard in ASTM D7467 and Sequence IVB testing. Documented 60,000-mile drain with oil analysis. Holds Cummins CES 20086, Detroit DFS 93K222, Volvo VDS-4.5, and Mack EOS-4.5 approvals.
Mobil Delvac 1 ESP 15W-40
Full synthetic. API CK-4. Strong OEM coverage across Cummins, Detroit, Volvo, and Mack. Widely used in Class 8 fleets. No published independent wear benchmark. No FA-4 variant in 15W-40 grade. No documented independent extended drain program. Group III base oil.
Spec Comparison
Side-by-side on every spec that matters for Class 8 fleet decisions.
| Spec | AMSOIL DME | Mobil Delvac 1 ESP |
|---|---|---|
| API Rating | ✓ CK-4 + FA-4 dual rated | ✓ CK-4 only |
| Wear Protection | 6× industry standard (ASTM D7467 + Seq. IVB) | No published independent data |
| Extended Drain | Documented 60,000 mi with oil analysis | OEM interval only |
| OEM Approvals | Cummins CES 20086, Detroit DFS 93K222, Volvo VDS-4.5, Mack EOS-4.5 | Cummins, Detroit, Volvo, Mack — similar coverage |
| FA-4 Available | Yes — DME is dual CK-4/FA-4 | Not in 15W-40 grade |
| Base Oil | Full synthetic PAO/ester blend | Full synthetic Group III |
| Cost Per Mile | Lower (extended drain offsets price) | Higher (more frequent drains) |
| Verdict | ✓ Wins on wear, FA-4, drain, cost-per-mile | Solid CK-4, no extended drain program |
The Key Differentiators
Where the gap between AMSOIL DME and Delvac 1 ESP actually shows up in fleet operations.
Independent Wear Data
AMSOIL DME is tested at 6× the wear protection of the industry standard in ASTM D7467 and Sequence IVB tests. These are standardized industry benchmarks. Mobil Delvac 1 ESP publishes no equivalent independent wear data for direct comparison.
FA-4 in One Product
DME is dual-rated CK-4/FA-4 in 15W-40. If your fleet runs Cummins X15 Efficiency Series or Detroit DD15 GHG17 engines that specify FA-4, DME covers them without switching products. Delvac 1 ESP 15W-40 does not carry FA-4 rating.
Drain Interval Math
At 60,000 miles vs a 25,000-mile OEM baseline, a 10-truck fleet cuts drain events from 48 per year to 20 per year. The higher upfront cost per quart inverts when you account for labour, downtime, filter costs, and disposal. Extended drain programs require oil analysis.
When Delvac 1 ESP Makes Sense
Mobil Delvac 1 ESP is a well-regarded CK-4 oil with solid OEM coverage and broad availability. If your fleet runs OEM intervals, does not need FA-4, and is purchasing through existing Mobil supply agreements, Delvac 1 ESP performs reliably. AMSOIL DME is the stronger call when you are running extended drains, need FA-4 dual rating, or want independently documented wear data behind your oil program.
Our Pick for Class 8 Diesel
AMSOIL Signature Series Max-Duty Synthetic 15W-40
- CK-4 + FA-4 dual rated
- 6× wear protection documented
- 60K mi extended drain
- Cummins CES 20086 + Detroit DFS 93K222 + Volvo VDS-4.5 + Mack EOS-4.5
Common Questions
For fleets running extended drains or needing FA-4 capability, yes. AMSOIL Signature Series Max-Duty (DME) is tested at 6× the wear protection of the industry standard, holds a documented 60,000-mile drain, and is dual-rated CK-4/FA-4. Mobil Delvac 1 ESP is a strong CK-4 oil with broad OEM coverage but publishes no equivalent independent wear data, has no FA-4 variant in the 15W-40 grade, and has no documented extended drain program.
No. Mobil Delvac 1 ESP 15W-40 is a CK-4 oil only. Mobil does offer a separate FA-4 product line, but Delvac 1 ESP 15W-40 does not carry FA-4 rating. AMSOIL Signature Series Max-Duty 15W-40 (DME) is dual-rated CK-4 and FA-4 — one product that covers both specifications.
Mobil Delvac 1 ESP is designed for OEM-recommended intervals, typically 15,000 to 25,000 miles for Class 8 line haul depending on application. Mobil does not publish an independent documented extended drain program for Delvac 1 ESP. AMSOIL Signature Series Max-Duty (DME) has a documented 60,000-mile extended drain claim backed by oil analysis.
AMSOIL Signature Series Max-Duty Synthetic 15W-40 (part number DME) is the direct replacement. Both are full synthetic CK-4 oils in 15W-40 with broad OEM coverage. DME adds independent wear data (6× industry standard), FA-4 dual rating, and a documented 60,000-mile extended drain. No engine flush is required — drain Delvac 1 ESP at your normal interval and fill with DME.
Yes. AMSOIL Signature Series Max-Duty (DME) holds Cummins CES 20086 and Detroit DFS 93K222 approvals, along with Volvo VDS-4.5 and Mack EOS-4.5. Mobil Delvac 1 ESP also covers Cummins, Detroit, Volvo, and Mack. Both products meet the same core OEM approval requirements — the difference is in wear data, FA-4 rating, and documented extended drain capability.