- An additive package is a pre-blended concentrate dosed into base oil at ~10–18% (PCMO) or 14–22% (HDDO) to meet a target spec such as API SP, API CK-4 or ACEA C3.
- Packages exist because components interact, OEM approvals are granted to specific packages, and each spec test sequence costs $500,000–$1M+.
- Core components: detergents (TBN, cleanliness), dispersants (soot suspension), ZDDP (antiwear), antioxidants and friction modifiers, plus corrosion and foam inhibitors.
- PCMO and HDDO packages differ in dispersant load, TBN and antioxidant robustness because diesel runs higher soot and longer drains.
- Select on three axes: target specification, base-oil group, and viscosity grade.
An engine oil additive package is a pre-blended concentrate containing most or all of the performance additives required to formulate a finished engine oil. The blender adds the package to base oil at a specified treat rate — typically 10–18% for passenger car motor oil (PCMO) and 14–22% for heavy-duty diesel (HDDO) — to produce an oil meeting a target specification such as API SP, API CK-4, or ACEA C3.
Why Use an Additive Package?
Lubricant blenders could theoretically source each additive separately and combine them. In practice, this is impractical for several reasons:
- Additive components interact: some combinations cause haze, precipitation, or reduced performance
- Engine OEM approvals (like Dexos, MB 229.5, VW 504/507) are granted to specific additive packages, not to individual components
- Specification testing (Sequence VIE, Mack T-12, Scania T13, etc.) is expensive — typically $500,000–$1M+ per test sequence
- Packages are optimised for a specific treat rate with a tested base oil group
Core Components in an Engine Oil Additive Package
A complete engine oil additive package typically contains:
- Detergents (10–30% of package): Overbased calcium sulfonates, phenates, and/or salicylates. Provide TBN reserve and high-temperature cleanliness. See our detergents range.
- Dispersants (25–45% of package): PIBSI (polyisobutenyl succinimide) mono or bis type, often borated. Keep soot and oxidation products suspended at low temperatures.
- ZDDP / Antiwear (8–15% of package): Primary and/or secondary alkyl ZDDP. Provides antiwear tribofilm + antioxidant activity.
- Antioxidants (3–8% of package): Hindered phenols (HDP) and/or aromatic amines (ADPA). Extend oxidative stability, especially in GDI and turbo applications with high oil temperatures.
- Friction modifiers (0–3% of package): MoDTC, GMO, or fatty acid amides. Required for “Resource Conserving” or “Fuel Economy” claims (ILSAC GF-6).
- Corrosion/rust inhibitors (1–3% of package): Protect yellow metals (copper, bronze) and ferrous surfaces in the presence of water ingress.
- Foam inhibitors (<0.1% of package): Silicone or acrylate defoamers. Prevent air entrainment that reduces film strength.
- Pour point depressant (0–2%): Sometimes included in the package; more commonly added separately by the blender.
- Viscosity index improver: Almost always added separately by the blender to adjust the viscosity grade.
PCMO vs. HDDO Additive Packages
Passenger car motor oil (PCMO) packages are formulated for gasoline engine conditions: moderate soot load, high sensitivity to phosphorus (catalytic converter protection), moderate TBN, and fuel economy priority. They are tested against API SP / ILSAC GF-6 sequences.
Heavy-duty diesel engine oil (HDDO) packages face very different conditions: high soot load (up to 6–8% soot by weight in spent oil), higher combustion acidity, and longer drain intervals (50,000–100,000 km). HDDO packages therefore use more dispersant, higher TBN detergents, and more robust antioxidant systems. They are tested to API CK-4/FA-4 or ACEA E sequences.
CheMost supplies both PCMO additive packages and heavy-duty diesel oil packages at competitive treat rates with flexible base oil group compatibility.
How to Select the Right Package
Selection depends on three factors:
- Target specification: API SP, ACEA C3, API CK-4, or an OEM approval?
- Base oil group: Group I/II/III mineral oil, or PAO/ester? Some packages are optimised for specific base oil groups.
- Viscosity grade: The package treat rate and VII selection determine whether you can reach 0W-20, 5W-30, or 15W-40.
For formulation assistance, our technical team can provide treat rate recommendations and blending guides for all CheMost additive packages. Browse the full range of additive components for custom formulation projects.
Frequently Asked Questions
Can I mix different additive packages to meet a specification?
No — additive packages are specifically designed and tested as complete systems. Mixing packages from different suppliers creates an untested combination that is unlikely to pass specification engine tests. If you need a specific performance level, speak to your additive supplier about packages already approved for that specification.
What is treat rate and how is it measured?
Treat rate is the percentage of additive package in the finished lubricant, by weight or volume. A PCMO package at 12% treat rate means 120 g of package per 880 g of base oil. The optimal treat rate is determined by the package developer through engine testing and is the minimum dose needed to pass all required performance tests.
Do additive packages have a shelf life?
Yes — most engine oil additive packages have a recommended storage life of 2–5 years when stored at controlled temperatures (below 30°C) in sealed containers away from moisture. Packages containing certain dispersant types may gel or precipitate on prolonged cold storage. Always check the TDS for specific storage conditions.
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