Lubricant Additives - Sulfonate Detergents Series: Low TBN Calcium Sulfonate (TBN 0–50 mgKOH/g) is the low-ash, low-SAPS-compatible detergent component for ACEA C1/C2/C3, API SP-RC, and ILSAC GF-6 engine oils, hydraulic oils, and rust preventive fluids. Sinolook supplies the full calcium sulfonate TBN range: Low (0–50) · Medium (150–300) · High (300–400) · Overbased (>400 mgKOH/g), plus Overbased Magnesium Sulfonate. COA, TDS, and SDS with every shipment.
Lubricant Additive · Sulfonate Detergent · Rust Inhibitor · Low-Ash / Low-SAPS
Low TBN Calcium Sulfonate
Neutral to Low-Overbased / TBN 0–50 mgKOH/g / Low-Ash Engine Oil Detergent / Rust Preventive Additive
| Chemical Type | Calcium alkylbenzene sulfonate in mineral oil diluent - neutral to low-overbased (CaCO₃ reserve: trace to minimal) |
| Structure | [C₁₈H₂₉–C₆H₄–SO₃⁻]₂ Ca²⁺ · Alkyl chain C₁₂–C₂₄ alkylaromatic; –SO₃⁻ head group ionically paired with Ca²⁺ |
| TBN Range | 0–50 mgKOH/g (ASTM D2896) |
| Physical State | Brown to dark brown transparent liquid; mild sulfonate odour; pumpable at ambient temperature |
| Specifications | ACEA C1/C2/C3 Compatible API SP / SP-RC ILSAC GF-6A/B ✓ REACH / TSCA |
| GHS Hazards | Combustible liquid FP ≥180°C Skin/Eye irritant H315/H319 |
What Is Low TBN Calcium Sulfonate?
Low TBN Calcium Sulfonate is a neutral to slightly overbased petroleum-derived detergent additive dissolved in mineral base oil. It is manufactured by sulfonating alkylbenzene feedstock (C₁₂–C₂₄ alkyl chain) to yield alkylbenzene sulfonic acid, then neutralising with calcium hydroxide or oxide to form the calcium sulfonate salt [R–C₆H₄–SO₃⁻]₂ Ca²⁺, and blending into Group I/II base oil at the required active content. At TBN 0–50 mgKOH/g, the product contains near-stoichiometric calcium sulfonate salt with little to no excess colloidal CaCO₃ alkalinity reserve.
The sulfonate head group's strong polarity drives tenacious adsorption onto metal surfaces, forming a hydrophobic protective film that displaces water, prevents surface oxidation, and keeps hot metal surfaces free from carbonaceous deposits and lacquer precursors. This film-forming detergency and rust inhibition operates independently of alkalinity reserve - making Low TBN calcium sulfonate uniquely effective where high-TBN grades cannot be used due to ACEA C-sequence sulphated ash limits for emission system protection.
| ● Low TBN (0–50) - This product | ACEA C1/C2/C3 · API SP-RC · Low-ash PCMO · Hydraulic oil · Rust preventive |
| ○ Medium TBN (150–300) | Standard PCMO · Light-duty diesel · Balanced TBN/ash |
| ○ High TBN (300–400) | Heavy-duty diesel · Commercial vehicle · High acid load |
| ○ Overbased (>400) | Marine TPEO · Bunker fuel · Maximum acid reserve |
Technical Specification
| Parameter | Specification | Test Method | Note |
|---|---|---|---|
| Appearance | Brown to dark brown transparent liquid | Visual | Clear, no sediment; mild characteristic sulfonate odour |
| TBN | 0–50 mgKOH/g | ASTM D2896 | Grade-specific TBN confirmed on COA; custom sub-grades (e.g. 15–25 mgKOH/g) available |
| Calcium Content | 1.5–3.5 wt% | ASTM D5185 / ICP-OES | Used to calculate sulphated ash in finished blend (Ca% × 3.4 ≈ S/A wt%) |
| Kinematic Viscosity @100°C | 8–20 cSt | ASTM D445 | Depends on diluent base oil grade; specify required viscosity at order |
| Flash Point (COC) | ≥ 180°C | ASTM D92 | Combustible liquid; standard industrial storage; not DG under IMDG/ADR/IATA |
| Density @20°C | 0.90–0.96 g/cm³ | ASTM D4052 | For volume-to-weight conversion in blending |
| Solubility | Fully miscible | - | Group I–V base stocks, PAO, ester base oil; verify in pure Group III/PAO by bench test |
| Packaging | 200 kg drum · 1000 L IBC · Flexitank | - | Steel drum standard; ISO tank for bulk ≥16 MT |
Performance Profile
High-Temperature Detergency
The sulfonate head group adsorbs onto hot metal surfaces, displacing combustion deposits, lacquers, and varnish precursors before they polymerise and harden. Film-forming detergency operates effectively at Low TBN without a large CaCO₃ reserve - particularly effective in thermal-cycling environments where deposits form from thermal degradation rather than acid accumulation.
Rust & Corrosion Protection
The hydrophobic alkyl chain creates a tenacious water-displacing film on ferrous surfaces, providing a physical barrier against moisture, oxygen, and salt spray. Effective at low treat rates (0.5–2.0 wt% in finished oil) - making Low TBN calcium sulfonate the standard rust inhibitor component in industrial lubricants and metal preservation fluids globally.
Low-SAPS / Low-Ash Compatibility ✓
ACEA C1/C2/C3/C5 and API SP-RC cap sulphated ash at 0.5–1.0 wt% to protect GPF, DPF, TWC, and SCR systems. Low TBN is the only calcium sulfonate grade that fits these limits at effective treat rates - Medium/High TBN grades carry 8–20% Ca vs Low TBN's 1.5–3.5%, contributing 3–10× more sulphated ash per wt% treat rate.
Thermal Stability
The aromatic sulfonate backbone resists free-radical chain oxidation - unlike ester-type additives, it does not participate readily in oil oxidation. Retains detergency and rust inhibition through extended drain intervals and sustained temperatures up to 120–150°C, suitable for long-drain low-ash engine oils and high-temperature hydraulic systems.
Applications & Formulation Guidance
1. Low-Ash / Low-SAPS Engine Oils - PCMO, Gasoline & Light-Duty Diesel
Modern PCMO targeting ACEA C-sequence or API SP-RC must limit sulphated ash to 0.5–1.0 wt% to protect GPF, DPF, TWC, and SCR aftertreatment. Low TBN Calcium Sulfonate provides the required surface cleanliness and rust protection while contributing far less sulphated ash per unit treat rate than any other calcium sulfonate TBN grade.
2. Hydraulic Oils - HM / HLP / HVLP
Hydraulic oils require rust and corrosion protection for cylinders, pump components, and steel reservoirs without impairing demulsibility or corroding yellow metals. Low TBN Ca sulfonate's near-neutral alkalinity is compatible with HM-type requirements - unlike overbased grades whose high alkalinity can impair demulsification and attack copper/brass at elevated treat rates.
3. Rust Preventive & Metal Preservation Oils
Calcium sulfonate is the most effective rust inhibitor active for metal preservation fluids. The hydrophobic film bonds strongly to ferrous surfaces, displacing water and salt for long-duration indoor storage protection. Low TBN grade is preferred over overbased grades for thin-film preservation coatings, where high alkalinity can reduce adhesion compatibility with subsequent painting or coating. Typical treat rate: 5–20 wt% in thin-film preservation oil; 1–5 wt% in long-term storage oil concentrate.
4. Industrial Gear Oils, Circulating Oils & Marine Lubricants
In industrial gear and circulating oils under moderate acid loads, Low TBN Ca sulfonate contributes detergency and rust inhibition without raising alkalinity to levels that could interfere with S-P EP additive packages. In marine stern tube and propulsion oils exposed to seawater ingress, the sulfonate film provides effective salt-water corrosion protection at low treat rates without requiring the high TBN reserve of marine TPEO grades.
Additive Compatibility & Blending Notes
| Co-Additive | Compatibility | Formulation Note |
|---|---|---|
| ZDDP (Primary / Secondary / Hybrid) | ● Excellent | Core engine oil pairing - Ca sulfonate for detergency; ZDDP for antiwear and antioxidancy. No adverse interaction at typical treat rates. |
| PIB Succinimide Dispersant (PIBSI) | ● Excellent | Complementary - sulfonate handles high-temp deposits; succinimide handles low-temp sludge/soot. Foundational pairing in all modern engine oil packages. |
| Phenolic Antioxidants (DBPC / BHT) | ● Excellent | No interaction; address different degradation pathways; routinely co-formulated without adjustment. |
| MoDTC / MoDTP Friction Modifiers | ● Good | Does not significantly interfere with MoDTC/MoDTP friction reduction at typical treat rates. |
| VI Improvers (OCP / PMA) | ● Good | Solubility-compatible. Verify shear stability of finished blend if high-MW OCP is used at high treat rate. |
| Yellow Metal Passivators (BTA / TTA) | ◑ Check | At treat rates >3 wt%, verify copper corrosion (ASTM D130) - Ca sulfonate may compete with BTA/TTA for surface adsorption. Adjust passivator level if copper strip rating exceeds 1b. |
| Medium / High TBN Ca Sulfonate | ● Good | Low + High TBN can be blended for intermediate TBN with controlled ash - useful for moderate-duty diesel needing more acid neutralisation than Low TBN alone while staying within ash budget. |
Frequently Asked Questions
Q: Why choose Low TBN over Medium or High TBN for ACEA C-sequence engine oils?
ACEA C1/C2/C3/C5 cap sulphated ash at 0.5–1.0 wt% to protect GPF, DPF, TWC, and SCR systems. Each gram of calcium in the finished oil contributes ~3.4 g of sulphated ash. At a 3 wt% treat rate: Low TBN (2.5% Ca) → ~0.25 wt% S/A; Medium TBN (typically ~10% Ca) → ~1.0 wt% S/A - already at the C3 limit before ZDDP ash is accounted for. Low TBN is the only grade that leaves sufficient ash headroom for ZDDP while meeting C-sequence requirements.
Q: Does Low TBN Calcium Sulfonate provide meaningful acid neutralisation?
At TBN 0–50 mgKOH/g, the product provides a small but real alkalinity reserve - adequate for mild acid control in gasoline PCMO and hydraulic systems where acid load is low. For heavy-duty diesel, long-drain, or high-sulphur-fuel applications with significant acid load, Medium TBN (150–300) or High TBN (300–400 mgKOH/g) should be used, or Low TBN blended with a higher TBN grade to achieve the TBN target within the available ash budget. Sinolook supplies all TBN grades.
Q: Is this product compatible with Group III / PAO / ester synthetic base stocks?
The active calcium sulfonate molecule is fully soluble in Group I through Group V base stocks - including Group III VHVI, PAO, polyol ester, and alkylnaphthalene. The product is supplied dissolved in a Group I/II mineral oil diluent. For formulations based entirely on Group III or PAO, confirm compatibility by a bench-scale mixing test at 80°C before scale-up, as solubility margins can vary by base stock composition.
Q: Calcium sulfonate vs magnesium sulfonate - when should I prefer each?
Magnesium (atomic weight 24 vs Ca 40) delivers more TBN per gram of sulphated ash. Overbased magnesium sulfonate is preferred in high-performance gasoline/turbocharged engines where maximising TBN within a tight ash budget is critical. Calcium sulfonates - including Low TBN - are preferred for rust preventive applications due to calcium's superior hydrophobic film-forming and water-displacing properties on ferrous metals. Many engine oil formulations blend both Ca and Mg sulfonates to balance TBN contribution, ash efficiency, and rust protection. Sinolook supplies Overbased Magnesium Sulfonate alongside the full Ca sulfonate TBN range.
Technical & Regulatory References
D2896 (TBN) · D5185 (metals by ICP-OES) · D92 (flash point COC) · D445 (kinematic viscosity) · D4052 (density) · D874 (sulphated ash) · D130 (copper strip corrosion)
ACEA 2021: C1 (S/A ≤0.5%), C2 (S/A ≤0.8%), C3 (S/A ≤0.8%), C5 (S/A ≤0.5%) · API SP / SP-RC · ILSAC GF-6A / GF-6B · ISO 11158 HM/HLP · DIN 51524 Part 2 (HLP) · MIL-C-16173 (preservation oil)
REACH registered · TSCA inventory listed · No SVHC designation · RoHS compliant · Transport: Combustible liquid FP ≥180°C - not classified dangerous goods under IMDG / ADR / IATA at standard packaging
Medium TBN Calcium Sulfonate (150–300 mgKOH/g) · High TBN Calcium Sulfonate (300–400 mgKOH/g) · Overbased Calcium Sulfonate (>400 mgKOH/g) · Overbased Magnesium Sulfonate · Overbased Barium Sulfonate · Primary ZDDP · PIB Succinimide Dispersant (PIBSI) · PMA Viscosity Index Improver
Buy Low TBN Calcium Sulfonate · Full TBN Range Available · COA / TDS / SDS per Shipment
Request Pricing, TDS & Qualification Sample
Specify your required TBN range (e.g. 20–30 mgKOH/g), calcium content target, viscosity grade of diluent oil, volume, and destination port. Competitive FOB pricing, full COA, TDS, and SDS provided within 12 hours. Qualification samples (1–5 L) at nominal charge. Full calcium sulfonate TBN range - Low / Medium / High / Overbased Ca and Overbased Mg - from a single source.
Related: Medium TBN Calcium Sulfonate · High TBN Calcium Sulfonate · Overbased Calcium Sulfonate · Overbased Magnesium Sulfonate · Primary ZDDP · PIB Succinimide Dispersant
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