The CI-4/SL/CF-4 engine oil additive complex refers to a multi-grade, high-performance additive package designed to meet the requirements of both diesel (CI-4, CF-4) and gasoline (SL) engine oil specifications.
This type of additive complex is widely used in multifunctional lubricants suitable for mixed fleet operations, where both gasoline and diesel engines (light-duty and heavy-duty) are in use.
🧪 What Do the Designations Mean?
| Code | Issued By | Engine Type | Description |
|---|---|---|---|
| CI-4 | API (2002) | Diesel | For high-speed, 4-stroke diesel engines, including EGR-equipped engines. High soot and acid handling. |
| SL | API (2001) | Gasoline | For gasoline engines. Good wear control, oxidation resistance, and deposit control. |
| CF-4 | API (1990) | Diesel | For older high-speed diesel engines, predecessor of CI-4. |
📌 An oil meeting CI-4/SL/CF-4 is backward-compatible with earlier API categories (e.g., CH-4, CG-4, SF).
🛢️ What Is in an Engine Oil Additive Complex?
A CI-4/SL/CF-4 additive package typically contains a balanced mix of additives to deliver protection across both diesel and gasoline engine needs.
🔧 Main Components & Functions:
| Additive Type | Function |
|---|---|
| Detergents (Calcium sulfonate/phenate) | Neutralize acids from fuel combustion (high TBN) |
| Dispersants (succinimide types) | Keep soot, sludge, and varnish in suspension |
| Anti-wear agents (ZDDP) | Prevent wear in valve trains, camshafts, etc. |
| Antioxidants (phenols, amines) | Resist oil oxidation and viscosity increase |
| Friction modifiers (optional) | Improve fuel economy in SL-spec oils |
| Rust & corrosion inhibitors | Protect internal metal surfaces |
| Viscosity index improvers (for multigrade) | Stabilize oil viscosity over temperature range |
| Pour point depressants | Improve cold-start performance |
| Foam inhibitors | Prevent foaming in high-RPM operation |
📈 Performance Expectations
| Property | Target Performance |
|---|---|
| High TBN (10–12 mg KOH/g) | Excellent acid neutralization |
| Soot handling (diesel) | Good dispersancy for up to ~6% soot in CI-4 engines |
| Wear control | Passes Sequence IIIF (SL) and Mack T-11 (CI-4) tests |
| Oxidation stability | Extended drain capability in mixed fleet |
| Low volatility | Reduces oil consumption and emissions |
🧴 Typical Treat Rate in Base Oil
| Base Oil Type | Treat Rate of Additive Package |
|---|---|
| Group I/II/III | 8–12 wt% depending on TBN and performance targets |
| Blended with VIIs and PPDs | to create 15W-40, 10W-30, etc. engine oils |
✅ Applications
- Mixed fleet lubricants (trucks, buses, pickups, passenger cars)
- On- and off-highway diesel engines (with or without EGR)
- Older gasoline engines requiring API SL or lower
- Agricultural and construction machinery
⚠️ Notes
- CI-4/SL oils are not suitable for modern DPF-equipped diesel engines (post-2007) requiring low-SAPS oils (like CJ-4, CK-4, FA-4).
- High phosphorus levels (from ZDDP) may harm catalytic converters in modern gasoline engines, which is why newer categories (API SN+, SP) have phosphorus limits.
🔧 Example Additive Package Composition
| Additive | Approx. wt% (in additive concentrate) |
|---|---|
| Calcium Sulfonate (TBN 300–400) | 25–35% |
| Succinimide Dispersant | 20–30% |
| ZDDP (Zn ~1.0%) | 5–10% |
| Phenolic/amine Antioxidants | 3–5% |
| Base oil carrier (Group II) | Balance |
🛠️ Summary
CI-4/SL/CF-4 engine oil additive complex provides:
- Strong protection for both diesel and gasoline engines
- Excellent cleanliness, anti-wear, and oxidation resistance
- Suited for older engines or regions using high-sulfur fuels
- A reliable solution for mixed fleet lubrication
CI-4/SL/CF-4 is the engine oil specification established by the American Petroleum Institute (API). It is a combination of three different performance categories of engine oils.
CI-4: This specification applies to diesel engine oils designed for high-speed four-stroke engines. It provides better control of soot thickening, piston deposits, valvetrain wear and oil consumption.
SL: This specification is for gasoline engine oils and focuses on deposit control, wear protection and oil oxidation stability. It is suitable for low emission and high performance gasoline engines.
CF-4: This specification also applies to diesel engine oils, but is designed for use with older, higher-sulfur fuels. CF-4 provides enhanced control of piston deposits, valvetrain wear, rust and bearing corrosion.
By combining these three specifications, CI-4/SL/CF-4 engine oil additive complexes provide a comprehensive formulation to meet the needs of gasoline and diesel engines. It provides high levels of engine protection, cleanliness and performance, ensuring optimal engine operation and longevity.
CI-4/SL/CF-4 engine oil additive complex is an important lubricant additive, mainly used to improve the performance of engine oil and extend engine life. This additive complex plays multiple roles in engine oil, such as cleaning, lubrication, anti-wear, and anti-rust, and is the key to ensuring the normal operation of the engine.
CI-4/SL/CF-4 engine oil additive complex is composed of a variety of additives, including detergents, dispersants, extreme pressure anti-wear agents, antioxidants, anti-corrosion and anti-rust agents, etc. These additives are mixed in a certain proportion and work synergistically to bring out the best performance of the additive complex. At the same time, in order to control the quality of additives, strict quality control is also required on the production and mixing process of additives to ensure the stability and consistency of the additive compound.
CI-4/SL/CF-4 engine oil additive complex has a wide range of application scenarios and can be applied to various types of engine oils. For example, in gasoline engine oil, this additive compound can effectively reduce engine friction, improve fuel economy, and extend engine life; in diesel engine oil, it can clean the fuel injection system, prevent the formation of carbon deposits and sludge, and protect the diesel engine. of normal operation.
CI-4/SL/CF-4 engine oil additive complex is a high-performance lubricant additive that can improve engine efficiency and life and reduce maintenance costs by optimizing the performance of engine oil. Its wide application and important role give it important application value and status in modern engine oils.