SHELL ROTELLA T6 vs MOBIL DELVAC 1 ESP
Two of the most common synthetic CK-4 oils in Class 8 fleets. Neither publishes independent wear data. Here’s what the specs actually say.
Shell Rotella T6 vs Mobil Delvac 1 ESP
Two of the most widely used CK-4 synthetic oils in Class 8 fleets. Here is what each actually offers.
Shell Rotella T6 15W-40
Full synthetic. API CK-4. Widely available at truck stops and dealers nationwide. Solid OEM coverage for Cummins, Detroit, Volvo, and Mack. No independent wear data published. No FA-4 variant available. No documented extended drain program. Group III base oil.
Mobil Delvac 1 ESP 15W-40
Full synthetic. API CK-4. Broad 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
An objective look at how these two oils compare across the specs that matter for Class 8 decisions.
| Spec | Shell Rotella T6 | Mobil Delvac 1 ESP |
|---|---|---|
| API Rating | ✓ CK-4 | ✓ CK-4 |
| FA-4 Available | ✗ No FA-4 variant | ✗ Not in 15W-40 grade |
| Extended Drain | Not documented | Not documented |
| OEM Approvals | Cummins, Detroit, Volvo, Mack — CK-4 coverage | Cummins, Detroit, Volvo VDS-4.5, Mack EOS-4.5, Detroit DFS 93K222 |
| Base Oil | Full synthetic Group III | Full synthetic Group III |
| Independent Wear Data | Not published | Not published |
| Price Per Quart | Similar range | Similar range |
| Verdict | Draw — solid OEM-interval oil | Draw — solid OEM-interval oil |
What the Specs Actually Tell You
Both oils check the same boxes at the OEM level. Here is where they land on each key decision factor.
OEM Approvals
Coverage is comparable. Both Rotella T6 and Delvac 1 ESP meet API CK-4 and cover Cummins, Detroit, Volvo, and Mack requirements. Delvac 1 ESP holds specific named approvals including Volvo VDS-4.5, Mack EOS-4.5, and Detroit DFS 93K222. Rotella T6 covers the same platforms under CK-4. Either product satisfies OEM oil requirements for these engines.
Wear Data
Neither Shell nor Mobil publishes independent wear data for Rotella T6 or Delvac 1 ESP comparable to ASTM D7467 or Sequence IVB benchmarks. Both products rely on API CK-4 certification as proof of performance, which sets a baseline but does not quantify relative wear protection between products.
Extended Drain
Neither product has a published extended drain program. Both are positioned for OEM-recommended intervals — typically 15,000 to 25,000 miles for Class 8 line haul. Running either oil beyond OEM intervals without oil analysis is unsupported by the manufacturer. If extended drains are a fleet cost target, neither of these products delivers a documented program.
Both Rotella T6 and Delvac 1 ESP are solid CK-4 oils for OEM intervals. Neither has a documented extended drain program. If extended drain intervals matter to your fleet, AMSOIL Signature Series Max-Duty (DME) is the only product in this category with independent wear data and a documented 60,000-mile drain.
Common Questions
At OEM drain intervals, both are solid CK-4 oils with similar OEM approvals and Group III synthetic base oil. Neither publishes independent wear data comparable to ASTM D7467 or Sequence IVB benchmarks. Neither has a documented extended drain program. For most fleets running standard OEM intervals, either product performs adequately. The choice typically comes down to availability, pricing, and supply agreements rather than a clear technical winner.
Shell does not publish an extended drain program for Rotella T6. Their documentation points to OEM-recommended intervals, typically 15,000 to 25,000 miles for Class 8 line haul. Running Rotella T6 beyond OEM intervals without oil analysis data is unsupported by the manufacturer. If extended drains are part of your fleet program, AMSOIL Signature Series Max-Duty (DME) is the only product in this category with a documented 60,000-mile drain backed by oil analysis.
Coverage is similar but not identical. Both hold approvals covering Cummins, Detroit, Volvo, and Mack requirements under API CK-4. Mobil Delvac 1 ESP holds specific named approvals including Mack EOS-4.5, Volvo VDS-4.5, and Detroit DFS 93K222. Shell Rotella T6 covers similar platforms. Neither holds FA-4 rating. For most Class 8 applications, both cover the same engine families.
Both Shell Rotella T6 and Mobil Delvac 1 ESP use Group III full synthetic base oil. Group III base oils are refined from petroleum to a very high purity level and meet the API definition of synthetic. Neither uses PAO (polyalphaolefin) or ester base oil. AMSOIL Signature Series Max-Duty (DME) uses a PAO/ester base oil, which typically offers a higher natural viscosity index and better film strength at thermal extremes.
Yes. If you need independently documented wear data and a documented extended drain program, AMSOIL Signature Series Max-Duty (DME) is the stronger choice. DME is tested at 6× the wear protection of the industry standard in ASTM D7467 and Sequence IVB tests, is dual-rated CK-4/FA-4, and has a documented 60,000-mile drain interval backed by oil analysis. Neither Rotella T6 nor Delvac 1 ESP publishes equivalent independent data or an extended drain program.