Diesel Engine Oil CF-4
Two SAE viscosity grades supported by supplied product inspection data.
A heavy-duty diesel engine oil range available in SAE 15W-40 and 20W-50. The page below presents the measured viscosity, cold-cranking, HTHS, flash point, pour point, cleanliness and foaming results from the supplied 2026 inspection reports.
A measured-data story for dependable diesel lubrication
The following benefits are explained using the actual physical-property results in the supplied inspection reports—not invented performance percentages.
High-Temperature Oil-Film Strength
Measured HTHS viscosity is 4.18 mPa·s for 15W-40 and 4.75 mPa·s for 20W-50, both above the report limit of 3.7 mPa·s.
See HTHS data →Controlled Low-Temperature Cranking
CCS results are 6,600 mPa·s at -20°C for 15W-40 and 8,307 mPa·s at -15°C for 20W-50, within their respective quality limits.
Compare grades →Volatility & Temperature Margin
Open-cup flash points are measured at 226°C and 230°C, while both grades report a pour point of -33°C.
View temperature data →Cleanliness & Foam Control
Both reports record no water and no mechanical impurities. Reported foaming results are 0/0 for every listed test sequence.
Review quality checks →For suitable older-generation and off-highway diesel equipment
Use CF-4 only when the engine or equipment manufacturer permits this API category and the selected SAE grade.
Heavy work. Clear grade selection.
Typical target equipment can include older commercial vehicles, construction machinery, agricultural equipment and stationary diesel engines—subject to OEM approval.
Commercial Diesel Fleets
Older trucks and buses whose manuals permit API CF-4 and the selected viscosity grade.
Construction Equipment
Suitable excavators, loaders, generators and site machinery operating under heavy loads.
Agricultural Machinery
Selected tractors, harvesters, pumps and farm engines where CF-4 is specified.
Stationary Diesel Engines
Industrial or standby equipment requiring the stated service category and viscosity.
Complete comparison of the supplied 15W-40 and 20W-50 reports
Values below are transcribed from the supplied Shengxiang product inspection reports. They represent the stated measured results and quality indices for those reports.
| Analysis item | 15W-40 index | 15W-40 result | 20W-50 index | 20W-50 result | Test method |
|---|---|---|---|---|---|
| Appearance | Transparent | Transparent | Transparent | Transparent | Visual inspection |
| Kinematic viscosity @ 100°C | 12.5–16.3 mm²/s | 14.7 mm²/s | 16.3–21.9 mm²/s | 19.40 mm²/s | GB/T 265 |
| Kinematic viscosity @ 40°C | Reported value | 110 mm²/s | Reported value | 177 mm²/s | GB/T 265 |
| Viscosity index | Reported value | 138 | Reported value | 126 | GB/T 2541 |
| Pour point | ≤ -25°C | -33°C | ≤ -20°C | -33°C | GB/T 3535 |
| Water content, volume fraction | None | None | None | None | GB/T 260 |
| Mechanical impurities, mass fraction | None | None | None | None | GB/T 511 |
| Flash point, open cup | ≥ 205°C | 226°C | ≥ 215°C | 230°C | GB/T 3536 |
| CCS low-temperature cranking | ≤ 7,000 mPa·s @ -20°C | 6,600 mPa·s | ≤ 9,500 mPa·s @ -15°C | 8,307 mPa·s | GB/T 6538 |
| HTHS viscosity @ 150°C, 10⁶ s⁻¹ | ≥ 3.7 mPa·s | 4.18 mPa·s | ≥ 3.7 mPa·s | 4.75 mPa·s | NB/SH/T 0703-2020 |
| Foaming tendency / stability | 24°C ≤20/0; 93.5°C ≤50/0; after 24°C ≤20/0 mL/mL | 0/0; 0/0; 0/0 | 24°C ≤20/0 mL/mL | 0/0 | GB/T 12579 |
| Determination | PASS | PASS | Inspection report | ||
Units and conditions are shown as stated or standardized from the supplied reports. Blank quality-index fields in the original reports are presented here as “Reported value.”
What each laboratory property tells the buyer
Kinematic Viscosity
Shows how readily the oil flows at 40°C and 100°C. The measured 20W-50 values are higher than the 15W-40 values, confirming the heavier operating-viscosity profile.
Viscosity Index
Indicates the rate of viscosity change with temperature. The reported VI is 138 for 15W-40 and 126 for 20W-50.
Pour Point
A laboratory indication of low-temperature flow. Both supplied reports show -33°C; it is not a direct engine-start temperature recommendation.
Open-Cup Flash Point
The lowest reported test temperature at which vapour can ignite momentarily under the specified method. Results are 226°C and 230°C.
Cold Cranking Simulator
Represents apparent viscosity during low-temperature cranking. The grades are tested at different specified temperatures, so the two CCS numbers should not be compared as if measured under identical conditions.
High-Temperature High-Shear
Reflects viscosity under severe high-temperature and high-shear test conditions. Both results exceed the stated minimum of 3.7 mPa·s.
15W-40 or 20W-50: select by the OEM manual—not by guesswork
The inspection data show clear physical differences. Suitability still depends on the engine design, ambient-temperature chart, operating condition and manufacturer recommendation.
15W-40
Broader cold-grade designationThe lower winter grade and lower measured operating viscosity may suit equipment whose OEM viscosity chart specifies SAE 15W-40.
20W-50
Higher operating viscosityThe higher measured viscosity and HTHS may fit selected engines and warmer-duty recommendations only where SAE 20W-50 is explicitly permitted.
Inspection, handling and publication essentials
What the supplied reports confirm
Both documents identify Shengxiang (Shandong) Energy Technology Co., Ltd. and state a final determination of Pass.
- Measured KV100 values fall inside the stated grade ranges.
- Pour point, flash point, CCS and HTHS results meet the stated report limits.
- No water or mechanical impurities are reported.
- Foaming results are reported as 0/0 for all listed sequences.
Recommended document practice
Keep marketing statements aligned with the authorized product documents and the intended market.
- Use the latest authorized TDS for published typical properties and product claims.
- Use the applicable SDS for safety, first-aid, transport and disposal information.
- Protect containers from water, dust, extreme heat and cross-contamination; keep them sealed and clearly identified.
- Set oil-drain intervals from the OEM schedule, duty severity and oil-analysis program—not from viscosity grade alone.
Important questions before selecting CF-4
Can CF-4 be used in every diesel engine?
No. Use it only where the engine or equipment manufacturer permits API CF-4. API currently marks CF-4 obsolete and cautions against its use in most diesel automotive engines built after 2009.
Which grade is thicker at operating temperature?
In the supplied reports, 20W-50 has higher measured kinematic viscosity at 40°C and 100°C and higher HTHS viscosity. This does not mean it is automatically better; the correct grade is the one permitted by the OEM.
Does a -33°C pour point mean the engine will start at -33°C?
No. Pour point is a laboratory low-flow property. Starting performance depends more directly on the specified winter grade, CCS requirements, battery, fuel system and engine condition.
Can the CCS figures be compared directly?
Not as identical-condition results. The 15W-40 value is measured at -20°C, while the 20W-50 value is measured at -15°C. Each should be judged against its own stated limit.
Are these values guaranteed for every production batch?
The supplied documents present measured results for their stated inspection reports. Use the latest authorized TDS for published typical values and the relevant certificate of analysis or inspection report for a specific batch.
How should the oil-change interval be decided?
Follow the engine manufacturer's service schedule and adjust only through approved severe-duty guidance or an oil-analysis program. The supplied reports do not state a drain interval.
