Two Caltex Delo 15W-40 grades dominate fleet conversations at AVDMM in Benoni: Delo Gold Ultra (API CI-4 / ACEA E7 territory — our top seller) and Delo 400 SLK (API CK-4 low-SAPS flagship). Both use ISOSYN Technology. They are not interchangeable just because the viscosity looks the same.
Side-by-side (workshop view)
| Delo Gold Ultra SAE 15W-40 | Delo 400 SLK SAE 15W-40 | |
|---|---|---|
| Typical API level | CI-4 (also covers older CH-4 / related claims per PDS) | CK-4 / CJ-4 / CI-4 PLUS backward support per PDS |
| ACEA (typical) | E7 class | E9 / E11 class (low SAPS) |
| SAPS / aftertreatment | Conventional HD chemistry — fine for many SCR/EGR fleets without DPF oil limits | Low-SAPS — designed for DPF + SCR / EGR modern diesels |
| Best fit | Older and mid-life mixed fleets on CI-4 / E7 specs | Newer OEM CK-4 / CJ-4 / low-SAPS specs; severe service; DPF-equipped |
| AVDMM role | Volume workhorse / top seller | Premium flagship when the book says CK-4 |
Always confirm against the current Astron / Caltex Product Data Sheet and the engine OEM manual for your exact model year.
When Delo Gold Ultra (CI-4) is the right call
- OEM asks for API CI-4 or ACEA E7 (or equivalent older HD diesel category the PDS supports).
- Fleet is mostly pre-DPF or engines that do not mandate low-SAPS CK-4/CJ-4 oil.
- You want one strong mineral 15W-40 for mixed on-road, construction, agriculture and gen-sets in that approval band.
- Cost per litre matters and the OEM has not moved you to CK-4.
Gold Ultra with ISOSYN Technology is built for soot control, deposit control and wear protection in high-speed four-stroke diesels — including many SCR/EGR layouts that still sit on CI-4/E7 chemistry.
When Delo 400 SLK (CK-4) is the right call
- OEM plate or manual specifies API CK-4, CJ-4, or ACEA E9/E11-type low-SAPS oil.
- Vehicles have diesel particulate filters (DPF) or other aftertreatment that needs controlled sulphated ash, phosphorus and sulphur.
- You want one premium oil that is backward-compatible across a mixed fleet that includes modern low-emission engines (still check each OEM).
- Severe on- and off-highway duty where the CK-4 chemistry is specified.
Note on fuel sulphur: low-SAPS oils generally have lower base number than classic HD oils. On modern low-sulphur diesel that is expected. If you ever run unusually high-sulphur fuel, drain strategy must be reviewed with a technical contact — do not assume CK-4 chemistry likes dirty fuel the same way older high-TBN oils did.
Decision rule for fleet managers
- Read the OEM oil spec — not the competitor’s quote.
- If the book says CK-4 / CJ-4 / low SAPS → 400 SLK.
- If the book says CI-4 / E7 and there is no DPF low-SAPS requirement → Gold Ultra is usually the economical, proven pick.
- Do not “downgrade” a CK-4 engine to CI-4 to save money; aftertreatment repairs cost more than the oil delta.
- Do not blindly put CK-4 in every old engine without checking the OEM — most accept it via backward compatibility, but confirm.
Stock and support from Benoni
AVDMM wholesales both grades for Gauteng collection or delivery planning. See the Delo range, workshop conversion notes on Diesel Lab, or contact the yard.
Also see: Diesel Lab — conversion charts & diesel tips. Related: What is ISOSYN Technology? · Havoline 20W-50 vs Ultra S 5W-40 · Condition Monitoring Ladder · CEF Diesel Wholesale Prices
Follow AVDMM: Facebook · LinkedIn · Instagram
WhatsApp us · Call office 011 422 1333