Technical Specifications
| Property | Unit | Typical Value | Test Method |
|---|---|---|---|
| Appearance | — | Brown red liquid | Visual |
| TBN | mgKOH/g | 420 | ASTM D2896 |
| Magnesium | % | 10.0 | ASTM D7751 |
| Flash Point | °C | >180 | ASTM D93 |
| Density at 20°C | kg/m³ | 1140 | ASTM D4052 |
| Viscosity at 100°C | mm²/s | 110 | ASTM D445 |
| Color | — | 2.0 | ASTM D1544 |
| Moisture content | % | 0.08 | ASTM D95 |
| Mechanical impurities | % | 0.03 | ASTM D473 |
* Typical values from batch production. Batch-specific COA available on request.
Technical content reviewed by the CheMost additives team · Specifications last reviewed
Molecular Structure
Supramolecular structure · overbased magnesium
Mg₂[R–C₆H₄–SO₃]₂ₓ·(MgCO₃)ᵧ
Colloidal MgCO₃ micelles stabilised by a magnesium sulfonate surfactant shell — the same overbased reserve mechanism as the calcium grades, but magnesium delivers the base at lower sulfated-ash contribution.
What Is Overbased Magnesium Sulfonate (M400)?
CheMost M400 is a synthetic overbased magnesium sulfonate detergent, made by sulfonating long-chain linear alkylbenzene and overbasing the magnesium sulfonate to a high reserve alkalinity — a TBN of 420 mgKOH/g at 10.0% magnesium. It is a metallic detergent, but built on magnesium rather than calcium.
It works by the same overbasing mechanism as the calcium grades — colloidal magnesium carbonate (MgCO₃) held inside a magnesium alkylbenzenesulfonate micelle — but the choice of metal is the point. Magnesium delivers a high base reserve while contributing lower sulfated ash than the equivalent calcium detergent, which makes M400 particularly suited to high-grade gasoline engine oils and gas-engine oils where ash and deposit behaviour matter.
How M400 Works
High base reserve, lower ash
The colloidal MgCO₃ core neutralises combustion and oxidation acids just as a calcium detergent does, but magnesium contributes the base at a lower sulfated-ash level — valuable where the finished oil has an ash ceiling. Because magnesium is a light metal, a high-magnesium grade like M400 (10.0%) can deliver that reserve at relatively low treat rates.
High-temperature cleanliness
The surfactant shell keeps deposit precursors suspended, controlling varnish and lacquer on hot surfaces through extended service.
Acid neutralisation
Reserve alkalinity neutralises the acidic by-products of combustion and oil oxidation, protecting against corrosive wear and helping hold viscosity and TBN through the drain interval.
Ash-tuning partner to calcium
Magnesium and calcium detergents behave differently on deposits and ash; blenders often use M400 alongside, or partly in place of, a calcium detergent to tune the ash and cleanliness profile of a package.
M400 vs C300 vs C400 — Choosing the Right Grade
All three are CheMost overbased sulfonate detergents in the same family; they differ in metal, base reserve and ash behaviour. M400 is the magnesium grade — the low-ash route to high base reserve.
| Property | C300 | C400 | M400 |
|---|---|---|---|
| Chemistry | High-base calcium sulfonate | Overbased calcium sulfonate | Overbased magnesium sulfonate |
| TBN (mgKOH/g) | 320 | 415 | 420 |
| Metal | 12.5% Ca | 15.85% Ca | 10.0% Mg |
| Viscosity at 100°C | 45 mm²/s | 100 mm²/s | 110 mm²/s |
| Ash behaviour | Calcium ash | Calcium ash | Lower ash than the calcium analogue |
| Best for | Balanced detergency + acid control for extended-drain HDDEO and high-sulphur-fuel oils | Maximum base reserve per unit treat for HDDEO, marine and high-sulphur-fuel packages | Lower-ash base reserve for high-grade gasoline and gas-engine oils |
Need the calcium grades instead? See C300 (balanced) and C400 (super-high-TBN booster).
Applications
M400 is used as the overbased magnesium detergent component in formulations targeting the categories below.
High-grade gasoline engine oils
The low-ash, high-base profile suits modern passenger-car oils, supporting cleanliness and acid control in formulations targeting current API S-category and ACEA gasoline requirements.
Gas-engine oils
Where ash must be controlled to manage valve and combustion-chamber deposits, magnesium’s lower ash contribution at high base reserve is an advantage.
Ash / deposit tuning in packages
Blended with calcium detergents to adjust the total ash and the deposit/cleanliness balance of a detergent–inhibitor package — the Ca:Mg ratio is a formulation lever.
Marine & stationary-diesel oils
Magnesium detergents are also used in marine and stationary-diesel service, where high acid-neutralisation is needed alongside good water tolerance, filterability and controlled ash.
Finished-oil OEM approvals (e.g. API, ACEA and OEM engine-test sequences) are held by the fully formulated oil, not by an individual additive component.
Treat Rate & TBN Contribution
The M400 technical data sheet gives a total treat range of 0.5–5.0 wt% to achieve the desired performance. Because TBN scales with treat, the first-order base contribution of M400 to the finished oil is:
e.g. 2 wt% → ≈ 8.4 mgKOH/g · 5 wt% → ≈ 21.0 mgKOH/g
Indicative starting points by application, derived from that relationship:
| Application | Indicative treat rate |
|---|---|
| Gasoline engine oils (as the magnesium detergent component) | 0.5–3 wt% |
| Gas-engine oils | 1–4 wt% |
| Ash-tuning alongside calcium | 0.5–2 wt% |
For context, total detergent treatment in engine oils typically runs 6–10 wt% (higher in marine cylinder oils). Because magnesium is carried at high weight-percent, M400 can deliver its base reserve at relatively low treat without sacrificing performance; its lower ash then lets a blender add reserve within an ash ceiling, often alongside a calcium detergent with the Ca:Mg ratio tuning the total ash.
Indicative starting points derived from the TBN/treat relationship above, not fixed dosages. M400 is one component of the additive system; the final treat rate must be confirmed against your target performance, ash/spec limit and co-additive package. CheMost can provide formulation and treat-rate support on request.
Formulating With M400 — Complementary Additives
A detergent covers acid control and hot-surface cleanliness; a balanced package pairs M400 with additives that cover the rest of the performance envelope:
Calcium detergents (C300 / C400)
Magnesium and calcium detergents are routinely combined: calcium carries much of the base economically, while magnesium tunes the ash and deposit behaviour. The Ca:Mg ratio is a formulation lever.
Ashless dispersants
The detergent–dispersant balance is the backbone of every crankcase package: M400 neutralises acids and cleans hot surfaces; an ashless dispersant suspends low-temperature soot and sludge.
ZDDP antiwear additives
ZDDP adds antiwear protection and secondary antioxidancy; detergent and ZDDP levels are balanced together to manage the oil’s total ash and acid-base budget.
Antioxidants
Phenolic and aminic antioxidants slow the oxidation that generates acids, extending oil life and preserving the usable base reserve.
Documentation, Qualification & Regulatory Support
Standard documentation — Certificate of Analysis (COA, per shipment), Technical Data Sheet (TDS) and Safety Data Sheet (SDS, GHS/CLP) — is provided. The full TDS is available on request rather than as a public download. Additional support is available on request:
Regulatory documentation
REACH, TSCA and country-specific market-registration documentation support available on request.
Third-party inspection
SGS / Intertek / BV pre-shipment inspection can be arranged on request.
Custom grades & packaging
Custom grades and packaging — metal drum, IBC, ISO tank.
Formulation support
Treat-rate calculation and formulation guidance from our technical team.
Packaging & Supply
M400 is stocked and shipped worldwide, with a typical lead time of 1–15 days and a 36-month shelf life at ambient temperature. Samples and quotations are answered within 12 hours.
Packaging
200 kg metal drum · 1000 kg IBC tank · ISO bulk.
Minimum order
1 drum or 1 IBC — no minimum order value.
Incoterms
FOB · CIF · EXW, to suit your freight arrangement.
Loading ports
All major Chinese ports.
Frequently Asked Questions
What is overbased magnesium sulfonate (M400)?
It is a synthetic magnesium sulfonate detergent overbased to a high reserve alkalinity — TBN 420 mgKOH/g at 10.0% magnesium. Colloidal magnesium carbonate is held inside a magnesium alkylbenzenesulfonate micelle, giving a concentrated acid-neutralising base that contributes lower sulfated ash than the calcium equivalent.
What is the difference between magnesium and calcium sulfonate detergents?
Both neutralise acids and clean hot surfaces by the same overbasing mechanism. The difference is the metal: magnesium delivers a high base reserve at lower sulfated ash than calcium, so it is favoured where ash must be limited — for example high-grade gasoline and gas-engine oils. Calcium is the lower-cost, balanced choice for most heavy-duty service.
Why use magnesium sulfonate in gasoline engine oils?
Modern gasoline-engine oils benefit from strong acid control and cleanliness without excessive ash. M400’s high TBN at lower ash lets a formulator add base reserve while staying within an ash target, which is why magnesium detergents are common in high-grade gasoline and gas-engine formulations.
What treat rate should I use for M400?
The TDS gives a total range of 0.5–5.0 wt%. As a first approximation the finished-oil base contribution is treat % × 420 ÷ 100 (so 5 wt% ≈ 21 mgKOH/g). The right level depends on your target TBN, ash limit and the rest of the package; our technical team can assist.
How is M400 supplied, and how fast can I get a sample?
M400 is supplied in 200 kg metal drums, 1000 kg IBC tanks and ISO bulk, and shipped worldwide with a 36-month shelf life. As a manufacturer and sourcing partner (Est. 2013), CheMost responds to sample and quotation requests within 12 hours.