Formulation Guide
Lubricant Additives Explained — What They Do and How Much to Use
A finished lubricant is essentially base oil plus an additive package. The additives — typically 10–25% of a finished engine oil — decide whether the oil passes API/BIS specifications, protects hardware and survives its service interval. This guide covers each additive family, what it does, typical treat rates, and how they combine into a DI package.
The two ways additives work
Additives are either surface-protective — they act at metal surfaces (anti-wear/ZDDP, EP, friction modifiers, corrosion inhibitors, detergents) — or bulk-protective, acting in the oil itself (dispersants, antioxidants, VII, PPD, anti-foam). A good package balances both against limits like SAPS (sulphated ash, phosphorus, sulphur), which modern low-emission specs cap tightly.
The additive families
Detergents
Keep high-temperature surfaces clean and neutralise combustion acids (measured as TBN). Common chemistries are overbased calcium and magnesium sulfonates, phenates and salicylates. Deep dive: Calcium Sulfonate Detergent →
Dispersants
Keep soot and oxidation by-products suspended so they don’t agglomerate into sludge — critical for diesel and stop-start engines. Usually ashless PIBSA-PAM succinimides. Deep dive: Succinimide Dispersant →
Anti-wear (ZDDP)
The workhorse anti-wear additive; zinc dialkyldithiophosphate forms a protective tribofilm on cams, tappets and bearings and acts as a secondary antioxidant. Deep dive: ZDDP Anti-Wear Additive →
Extreme-pressure (EP)
Protect gears under shock and high load — essential in GL-5 gear oils. Sulphur-phosphorus and borate chemistries. Deep dive: EP Additive →
Friction modifiers
Lower friction for fuel economy and smooth operation — organic FM and MoDTC chemistries. Deep dive: Friction Modifier →
Antioxidants
Slow the oxidation that thickens oil and forms acids and deposits — the main driver of oil life. Phenolic and aminic types work synergistically with ZDDP. Deep dive: Antioxidant Additive →
Viscosity index improvers (VII)
Polymers that make viscosity change less with temperature — the basis of multigrade oils. OCP, PMA and star polymers, selected for shear stability. Deep dive: VII Polymer →
Pour point depressants (PPD)
Wax-crystal modifiers (usually PMA) that keep oil flowing at low temperature — chosen by SAE winter grade. Deep dive: Pour Point Depressant →
Corrosion / rust inhibitors
Protect ferrous and yellow metals from acids, water and oxidation products. Deep dive: Corrosion Inhibitor →
Anti-foam
Silicone or non-silicone additives that break foam which would otherwise starve the oil film. Dosed in ppm. Deep dive: Antifoaming Agent →
What is a DI (Detergent-Inhibitor) package?
Rather than blend every additive separately, most formulators buy a DI package — a pre-balanced concentrate of detergents, dispersants, anti-wear, antioxidants and inhibitors — then add VII and PPD to hit the viscosity grade. A DI package shortcuts development but costs more; custom component blending can cut additive cost 8–15% at scale, but needs formulation control and a QC lab. See our engine oil DI package breakdown and additive package supplier comparison — including alternatives to Lubrizol, Afton HiTEC, Infineum and Chevron Oronite.
Typical treat-rate reference (finished engine oil)
| Additive family | Typical treat rate | Primary job |
|---|---|---|
| Detergent | 1.0–3.0% | Clean surfaces, neutralise acid (TBN) |
| Dispersant | 2.0–6.0% | Suspend soot / sludge |
| ZDDP (anti-wear) | 0.8–1.4% | Anti-wear tribofilm, secondary antioxidant |
| Antioxidant | 0.3–1.5% | Extend oil life |
| VII | 3–12% (grade-dependent) | Multigrade viscosity |
| PPD | 0.1–0.5% | Low-temperature flow |
| Anti-foam | 3–15 ppm | Break foam |
Ranges are indicative; the correct treat rate depends on base oil, target spec (API/ACEA/BIS) and SAPS limits. Getting this balance right is what additive development and lubricant oil formulation deliver.
Explore each additive chemistry
Lubechem formulates additive systems for manufacturers. If you are building a package rather than reading one, see additive development. Otherwise stay in the lubricant library.
Frequently asked questions
What percentage of engine oil is additives?
Can I formulate without a commercial DI package?
What is SAPS and why does it limit additives?
Which additive controls oil thickening over time?
How do I choose a viscosity index improver (VII)?
More on oils, greases
and what additives do in them
This page is a map of additive families. The lubricant library has which/when guides and literature explainers. Additive development is there if you manufacture.