Diesel Engine Oil Guide: API CK-4 vs FA-4 Explained
Heavy-duty diesel engine oil (HDDO), also called HDEO, is the crankcase lubricant engineered for compression-ignition engines in trucks, buses, off-highway and construction equipment, agricultural machinery, and diesel generator sets. The decision that matters most to a buyer is which specification family — commonly API CK-4 or FA-4, and where relevant an ACEA E-sequence, a JASO grade, and the right SAE viscosity — the specific engine's OEM manual calls for. These products are not interchangeable, and specifying the wrong one can leave an engine under-protected or void a warranty. This guide explains what each specification means, how to choose between API CK-4 and FA-4, why "low-SAPS" oils exist, and what to check before requesting a quote for diesel engine oil from a supplier in the Altonex Global Diesel Engine Oils category.
What Is Heavy-Duty Diesel Engine Oil, and How Is It Different From Regular Motor Oil?
HDDO carries materially higher detergent and dispersant treat rates than passenger-car motor oil (PCMO), because diesel combustion generates far more soot than gasoline combustion — soot loading in used oil can reach roughly 3–6% by weight — along with more acidic combustion byproducts that must be neutralized. HDDO also tends toward heavier viscosity grades than PCMO: common HDDO grades include 15W-40 and 10W-40, versus PCMO's typical 5W-30, 5W-20 or 0W-20.
The two families are not interchangeable. PCMO generally lacks the dispersancy to control diesel soot, risking abrasive wear and rapid depletion of the oil's acid-neutralizing reserve (TBN) in a diesel engine, while HDDO's stronger dispersant chemistry can be incompatible with seal materials specified for PCMO. Buyers sourcing for a mixed fleet should treat diesel and gasoline engine oil as separate product lines.
Diesel Engine Oil Specs at a Glance
The table below orients buyers to the specification families most often referenced on a diesel engine oil technical data sheet. It is a starting point, not a substitute for checking the specific engine manufacturer's current approval requirements.
| Specification family | Current designations | Typical duty focus | HTHS viscosity |
|---|---|---|---|
| API (US) | CK-4, FA-4, CJ-4, CI-4, CH-4 (all current); "CI-4 PLUS" is a supplemental designation, not a standalone license | On-highway trucks/buses, Tier 4 off-highway equipment | CK-4/CJ-4/CI-4 reported ≥3.5 cP; FA-4 2.9–3.2 cP |
| ACEA (Europe) | E4, E7 (full-SAPS); E8, E11 (low-SAPS, replaced E6/E9); F01 (new, 2024 edition) | European on- and off-highway diesel engines | E4/E7/E8/E11 ≥3.5 cP; F01 2.9–3.2 cP |
| JASO (Japan) | DH-2 heavy-duty low-ash (current standard M 355:2024); DL-1/DL-2 light-to-moderate duty | DH-2 = heavy trucks/buses; DL-1/DL-2 = passenger and light-truck diesels | Not the primary differentiator — ash/after-treatment compatibility is |
| SAE J300 (viscosity) | Common HDDO grades: 15W-40, 10W-40, 10W-30; 5W-30 emerging | Grade depends on OEM factory-fill spec and climate | Not applicable — SAE grades measure viscosity, not performance level |
Important: "0W-20" is a passenger-car/light-duty grade, not a recognized heavy-duty diesel engine oil grade. Where a low-HTHS, fuel-economy oil is specified (API FA-4 or ACEA F01), the applicable grade family is XW-30 only — in practice mostly 10W-30, with 5W-30 also used. There is no "FA-4 0W-20" product.
What Do API's Diesel Engine Oil Categories (CK-4, FA-4, CJ-4, CI-4) Mean?
The American Petroleum Institute (API) licenses diesel engine oil categories through its Engine Oil Licensing and Certification System (EOLCS). API currently lists CK-4, FA-4, CJ-4, CI-4 and CH-4 as current categories; CG-4 and older designations are obsolete.
CK-4 (introduced 1 December 2016) is backward compatible with most applications that previously called for CJ-4, and its scope covers the performance levels of CI-4 and the enhanced "CI-4 PLUS" designation. It is the broadest-coverage current heavy-duty category — a practical single-product choice for a mixed fleet of older and newer engines — and is formulated to remain effective on diesel fuel with sulfur content up to 500 ppm.
FA-4 (same introduction date) is a narrower category built around a lower high-temperature/high-shear (HTHS) viscosity window of 2.9–3.2 cP, intended to improve fuel economy in engines specifically engineered by their OEM to use it — in practice, mostly 2017-model-year-and-newer on-highway engines. FA-4 is not broadly backward compatible and is licensed only in XW-30 grades; do not treat it as a drop-in for CK-4, CJ-4 or CI-4 without OEM confirmation.
One frequent point of confusion: "CI-4 PLUS" is not a separate, standalone API-licensed category. It is an enhanced performance designation within CI-4, referenced because CK-4 and CJ-4 remain backward compatible with engines that previously used CI-4 or CI-4 PLUS oil. A datasheet presenting "CI-4+" as its own current license tier is describing it inaccurately.
How to Choose: API CK-4 vs FA-4 (and ACEA's Standard E-Series vs F01)
For most B2B buyers, the choice comes down to one question: does the specific engine's OEM manual explicitly call for FA-4 (or an ACEA F01-class product)? If not, CK-4 — or the equivalent standard-HTHS ACEA E4/E7/E8/E11 tier — is the safer, broadly applicable default.
- Default to CK-4 unless told otherwise. It is backward compatible with CJ-4/CI-4-era requirements and applies across on-highway and off-highway, older and newer diesel engines, including Tier 4 non-road equipment.
- Use FA-4 only when the engine was specifically engineered by its OEM for it — virtually always a 2017-model-year-or-newer on-highway engine. FA-4 is licensed only in XW-30 grades at its lower 2.9–3.2 cP HTHS window; never request or expect an FA-4 product in 0W-20.
- On the ACEA side, the equivalent decision is E4/E7/E8/E11 (≥3.5 cP HTHS) versus F01 — new in ACEA's December 2024 (Rev 1) edition, also restricted to XW-30 grades at the same 2.9–3.2 cP HTHS window as FA-4. F01 is a narrow, fuel-economy tier for the newest Euro VI/Stage V engines it is designed for, not a general fleet upgrade.
- When in doubt, ask the supplier for the engine manufacturer's own current approval list or approval letter rather than relying on a datasheet's general "suitable for" language.
This is the single most consequential specification decision in this category: it protects warranty coverage and engine durability. Using FA-4 in an engine that was not designed for it — or assuming any heavy-duty XW-30 oil is automatically FA-4-licensed — is one of the more costly sourcing mistakes a buyer can make.
What Do the ACEA E4, E7, E8, E11 and F01 Ratings Mean?
ACEA (the European Automobile Manufacturers' Association) publishes its own heavy-duty engine oil sequences, revised periodically. E4 and E7 are full-SAPS categories with no DPF-compatibility requirement, aimed at the most severe and less severe duty cycles with extended or medium drain intervals. E8 replaced the older E6, and E11 replaced the older E9; both are low-SAPS categories compatible with DPF/SCR/EGR after-treatment, with an ash ceiling reported at 1.0% or lower, and E11 applies tighter cleanliness limits than E8. F01 is new in ACEA's December 2024 (Rev 1) edition — a low-HTHS (2.9–3.2 cP), XW-30-only, fuel-economy category derived from the E11 performance level for the latest Euro VI/Stage V engines.
Older E6 and E9 designations are now obsolete, with 2016-sequence claims reportedly marketable only until 1 May 2024. Under the 2024 edition, new claims were reportedly permitted from 18 December 2024, becoming mandatory for all new claims from 18 December 2025 — buyers should confirm current effective dates with the supplier, since sequence transition dates are periodically revised.
The exact numeric ash, phosphorus and sulfur ceilings separating full-SAPS E4/E7 from low-SAPS E8/E11 vary by source; buyers who need precise SAPS percentages for a compliance file should request them directly from the supplier's technical data sheet rather than a general summary.
JASO DH-2 vs DL-1: Which One Do I Need?
JASO (the Japanese Automotive Standards Organization) maintains its own diesel engine oil classification, currently JASO M 355:2024. A common and costly sourcing error is treating JASO's DH and DL categories as interchangeable — they are not.
DH-2 is the heavy-duty, low sulfated-ash category for DPF-equipped trucks and buses, typically paired with low-sulfur diesel fuel — the category to request when sourcing genuine heavy-truck or bus diesel engine oil for Japanese-brand engines. An older DH-1 designation also exists: heavy-duty, but with higher sulfated ash and not intended for after-treatment devices.
DL-1, by contrast, is a light-to-moderate-duty category for passenger-car and light-truck diesel engines with a DPF — broadly the JASO peer of ACEA's light-duty C-sequence, not the heavy-truck tier. DL-2, added in 2021, is also a light-duty-family category. A buyer sourcing oil for a heavy on-highway truck or bus should request DH-2, not DL-1 or DL-2.
Which SAE Viscosity Grade Is Right — 15W-40, 10W-30, 10W-40, or 5W-30?
SAE J300 is the governing viscosity-classification standard for engine oils, pairing a winter viscosity rating (0W, 5W, 10W, 15W, 20W, 25W) with a high-temperature number (8, 12, 16, 20, 30, 40, 50, 60).
15W-40 has long served as the universal standard for diesel fleets and remains a very common global HDDO grade, especially with full-SAPS CK-4/CJ-4-class oils. 10W-30 is reported as the OEM factory-fill standard at several major on-highway engine makers, displacing 15W-40 as new-truck factory fill, and is also the primary grade for FA-4 products. 10W-40 is a common "shoulder" grade referenced in several European OEM low-ash approval sheets. 5W-30 is emerging for the most fuel-economy-focused FA-4 and ACEA F01 applications.
20W-50 is reported as common in some tropical, high-ambient-temperature markets for older engine populations — buyers there should confirm current OEM guidance rather than assume this remains the recommendation for late-model engines. In every climate, the deciding factor should be the specific engine manufacturer's factory-fill or service-fill recommendation, not regional habit alone.
Why Do Modern Diesel Oils Need to Be "Low-SAPS"?
SAPS stands for Sulfated Ash, Phosphorus and Sulfur — three elements that matter because of how they interact with modern emissions after-treatment hardware:
- Ash is the incombustible mineral residue left when metallic detergent and anti-wear additives burn. Unlike the soot a diesel particulate filter (DPF) is designed to burn off, ash accumulates permanently in the filter, forcing more frequent regeneration and eventually shortening filter life.
- Phosphorus, largely from anti-wear additive chemistry, can coat and gradually reduce the effectiveness of emissions-catalyst surfaces.
- Sulfur compounds can interfere with the chemistry of Selective Catalytic Reduction (SCR) systems used to reduce NOx emissions.
Low-SAPS oils (API CJ-4/CK-4-class, ACEA E8/E11, JASO DH-2) limit these three elements to protect DPF, SCR and EGR after-treatment on modern emissions-compliant engines. Full-SAPS oils (ACEA E4/E7) carry a higher ash ceiling and suit engines without this hardware. At the OEM level, Deutz illustrates the point clearly: it maintains a separate low-ash "LA" tier within its own quality classification for DPF-fitted engines, distinct from its conventional non-LA tier.
Practical rule: check whether the target engine has a DPF, SCR or advanced EGR system. If so, a low-SAPS oil is very likely required; if not, a full-SAPS, higher-TBN oil may be the more durable choice. Always confirm against the specific engine's OEM manual.
What OEM Approvals Should I Ask For, and What's the Difference Between "Approved" and "Meets"?
Beyond the API/ACEA/JASO category, many fleet and OE-tier buyers also require a specific engine manufacturer's approval. Two layers matter here, and confusing them is a common buyer mistake.
The API layer: a product bearing the API "donut" (Service Symbol) or "starburst" (Certification Mark) has been formally licensed through API's EOLCS program — its formulation is on file with API and subject to ongoing market-sample re-testing. A product that merely claims to "meet API CK-4" without being licensed is not entitled to display either mark.
The OEM layer: "OEM approved" means the product was formally submitted to the engine manufacturer (or an OEM-designated laboratory) for testing, and the OEM issued a dated approval — typically valid for a limited period, commonly cited in the range of one to five years. "Meets the OEM specification" means the blender formulated to the OEM's published requirements without independent OEM verification — a self-declared compliance claim.
Several major engine manufacturers publish their own branded approval codes alongside the API/ACEA framework — for example, Cummins (CES 20086 for CK-4-class, CES 20087 for FA-4-class), Volvo Trucks/Mack (VDS-4.5, plus a newer VDS-5 tier reported for select 2021-and-later GHG-compliant engines only), Caterpillar (ECF-3), and Deutz (its low-ash "LA" tier); Mercedes-Benz/Daimler Truck and MAN maintain their own sheet numbers. Exact companion-approval bundles — which older codes a newer approval remains backward compatible with — change periodically by engine model year and region, so this article does not reproduce a detailed compatibility table.
Buyer instruction: for warranty-sensitive or OE-tier purchases, always request the current dated OEM approval letter, or check the OEM's own published approved-product list, directly from the supplier — not just a datasheet "meets" statement.
Does My Local Diesel Fuel Quality Affect Which Oil I Should Specify?
Yes — and for a global export marketplace, this is one of the more overlooked buyer-choice factors. API's own description of the CK-4 category states it is formulated for diesel fuel with sulfur content up to 500 ppm, meaning CK-4/CJ-4-class oils remain an appropriate, tolerant choice in markets that have not fully transitioned to ultra-low-sulfur diesel (ULSD).
Globally, ULSD adoption is uneven: some export markets have moved to very low-sulfur diesel, while others still supply a higher-sulfur, transitional grade, particularly across parts of Southeast Asia, the Middle East, South America and sub-Saharan Africa, where regulatory timelines and refining infrastructure delay full ULSD transition. Exact sulfur-content figures vary by country and change over time, so this article does not cite specific percentages — confirm current fuel-quality regulation for any destination market directly rather than assume a figure from a general summary.
The practical takeaway: a low-SAPS, DPF-oriented product (ACEA E8/E11, JASO DH-2, or an OEM low-ash "LA"-class tier) suits markets where ULSD and DPF-equipped engines are actually deployed. In markets still running higher-sulfur diesel without widespread DPF adoption, a full-SAPS, higher-TBN CK-4/CJ-4-class or ACEA E4/E7 product is often the more durable choice. Factor in the destination market's fuel-quality reality, not only the engine's model year.
Packaging, MOQ and Export Documentation for B2B Diesel Engine Oil Buyers
Diesel engine oil is traded across a wide range of pack formats in B2B export, from retail-style bottles through bulk drums and intermediate bulk containers (IBCs). Minimum order quantities (MOQs) are set independently by each supplier and vary by pack format, product and destination — the ranges below are illustrative only and must be confirmed directly with the supplier via RFQ.
| Pack format | Illustrative MOQ range (supplier-dependent) |
|---|---|
| 1 L retail bottle / 4 L jerrycan | Roughly low thousands to a few thousand units per SKU |
| 20 L jerrycan/pail | Roughly hundreds to about a thousand units per SKU; smaller trial quantities sometimes available for new customers |
| 200 L / 208 L drum | Roughly a pallet's worth upward; a 20-foot general-purpose container typically holds on the order of dozens of palletized drums |
| 1,000 L IBC | Roughly single-digit to low double-digit units; a 20-foot container floor layer typically holds on the order of ten IBCs |
| Private-label custom packaging | Typically several thousand units per SKU, usually constrained by print-run tooling rather than liquid volume |
A complete export shipment typically involves several standard documents. The Technical Data Sheet (TDS) gives nominal or typical properties — viscosity, HTHS, TBN, flash and pour point — and intended suitability. The Certificate of Analysis (CoA) is batch-specific and confirms the actual shipped batch meets the claimed specification; it is typically the most closely scrutinized document by OE-tier fleet buyers. The Safety Data Sheet (SDS) supports the buyer's handling, storage, PPE and transport risk assessment. For customs purposes, finished lubricating oils generally fall under Harmonized System (HS) Chapter 27, heading 2710.19; some countries maintain a more specific national subheading for automotive/diesel/marine engine oils. Because classification varies by destination and is periodically revised, always confirm the applicable HS code with the destination country's customs authority or a licensed broker before shipment.
A well-formed RFQ should state: the SAE viscosity grade needed; the API and/or ACEA and/or JASO category required; any specific OEM approval required; the intended application (on-highway, off-highway, agricultural, or genset/stationary); the preferred packaging format and indicative quantity; the destination country and preferred Incoterm; and which documents (TDS, CoA, SDS, Certificate of Origin) will be required with the shipment.
Altonex Global is a B2B trade-discovery and RFQ marketplace connecting buyers with independent suppliers of lubricants and fast-moving auto spare parts for export. Altonex Global does not manufacture, blend, certify or sell diesel engine oil, and does not set or guarantee any product's specification, price or stock availability — each listed supplier is independently responsible for its own product claims, quotations, documentation and after-sales support. To source diesel engine oil matching your engine's OEM requirements, browse the Diesel Engine Oils category and use the Request Quote / Contact Supplier / Export Inquiry option on the relevant listing, including the specification details outlined above. For further sourcing guides, visit the Altonex Global Knowledge Hub.