What Is SN500 Base Oil? Applications, Specifications and Industrial Uses

Understanding SN500 base oil

SN500 is a Group I solvent-neutral base oil. Under the API 1509 classification, Group I covers base stocks with less than 90% saturates and more than 0.03% sulfur, with a viscosity index of 80 to 120. These are the original mineral base oils produced by classical solvent refining of vacuum gas oil — a route operated worldwide for more than seventy years and still dominant in Asia and the Middle East.

The solvent refining process

Group I production begins with vacuum distillation of long residue from atmospheric crude distillation. The vacuum gas oil fractions are processed through three classical steps: solvent extraction (using furfural or NMP) to remove aromatic compounds, solvent dewaxing (using MEK/toluene) to lower the pour point, and hydrofinishing to improve color and oxidation behavior. The output is a family of solvent neutrals — typically SN100, SN150, SN500 and SN650 — each defined by a viscosity range. SN500 is the heaviest fully-fluid grade in the standard solvent-neutral lineup; bright stock occupies the still heavier residual slot.

What "SN500" actually means

The letters SN stand for Solvent Neutral — solvent-refined, with a neutral pH after finishing. The number 500 refers to the Saybolt Universal Seconds (SUS) viscosity measured at 100°F, an imperial unit still used in the lubricants trade. SN500 therefore has a viscosity of approximately 500 SUS at 100°F, equivalent to a kinematic viscosity of roughly 90–110 cSt at 40°C and 10.5–11.5 cSt at 100°C, with a viscosity index typically in the 95–100 range.

This places SN500 firmly in the heavy-viscosity bracket — substantially heavier than SN150 and one of the primary base stocks used to lift finished lubricant viscosity into SAE 40, SAE 50, ISO VG 100, ISO VG 150 and gear-oil territory.

Typical SN500 specifications

The table below summarizes typical specification ranges for Group I SN500 that buyers should expect to see on a Certificate of Analysis (CoA). Use it as a reference frame when evaluating supplier offers.

Disclaimer: Actual specifications vary by refinery and producer. Always request a batch-specific Certificate of Analysis (CoA) and the latest Technical Data Sheet (TDS) before nomination.

Common industrial applications of SN500

SN500's heavy viscosity, predictable additive response and competitive pricing make it the default heavy neutral across a wide range of lubricant categories.

• Automotive lubricants — monograde diesel engine oils (SAE 40, SAE 50) for older fleets and heavy-duty trucks, multigrade engine oils such as 15W-40 and 20W-50 where SN500 is the dominant heavy fraction blended with SN150 and a VI improver.
• Marine lubricants — trunk piston engine oils, crosshead system oils, marine cylinder oils and stern tube lubricants where SN500 contributes viscosity, film strength and price stability.
• Industrial gear oils — ISO VG 100, VG 150 and VG 220 industrial gear oils, open gear lubricants and worm gear oils where SN500 provides the primary high-viscosity base.
• Heavy-duty lubricants — railway engine oils, off-highway hydraulic fluids and slideway oils where Group I robustness and additive tolerance are preferred over hydroprocessed grades.
• Grease manufacturing — lithium, calcium, complex soap and bentonite greases where SN500 lifts base-oil viscosity, controls penetration and supports dropping point and shear stability.
• Blending applications — process oils, rust preventives, transformer oil blending stock (with appropriate finishing) and a wide range of formulated industrial fluids.

SN500 vs SN150

SN500 and SN150 are the two workhorse Group I solvent-neutral grades. They are almost always specified together because blends of light and heavy neutrals are what allow formulators to hit specific finished-product viscosity grades.

In practical formulation, a 20W-50 engine oil is typically 60–70% SN500 with 30–40% SN150, while an SAE 40 marine oil can run above 80% SN500. The ratio is the formulator's primary lever — which is why secure parallel supply of both grades is essential for any continuous lubricant production line.

SN500 vs Group II 500N

SN500 and Group II 500N occupy the same viscosity slot but come from fundamentally different refining routes. Choosing between them is one of the most frequent procurement decisions for lubricant manufacturers.

Refining differences

SN500 is produced by classical solvent refining — extraction, dewaxing and hydrofinishing. Group II 500N is produced by severe hydrocracking and hydroisomerization, a more capital-intensive process that saturates aromatic rings and removes sulfur and nitrogen at the molecular level. The result is a fundamentally cleaner, lighter-colored and more uniform base oil.

Oxidation stability

Group II 500N delivers substantially better oxidation stability than SN500. Higher saturates and lower aromatics translate into longer drain intervals, lighter additive treat rates and improved high-temperature performance. SN500 still meets the requirements of most industrial gear oil, marine oil and grease specifications, but it cannot match Group II in long-drain passenger car engine oils.

Sulfur content

By API definition, Group I SN500 contains > 0.03% sulfur and < 90% saturates; Group II 500N contains ≤ 0.03% sulfur and ≥ 90% saturates. The lower sulfur in 500N is decisive for low-SAPS engine oils and modern emission-system-compatible formulations.

Cost considerations

SN500 generally trades at a discount to Group II 500N — frequently USD 50–150 per metric tonne lower on a CFR basis, depending on the spread between solvent-refined and hydroprocessed capacity in the region. For high-volume industrial gear oils, marine lubricants and grease production, this cost gap is material.

Buyer preferences

SN500 remains the preferred heavy neutral for industrial, marine and grease applications and for monograde engine oils serving legacy fleets. Group II 500N dominates premium multigrade engine oils, modern transmission fluids and OEM-approved hydraulics that demand longer service life. For the highest tier of passenger car motor oils, buyers move further up to Group III base oils.

Global supply sources for SN500

Group I capacity has been rationalized across Europe and North America over the last decade, but solvent-refined SN500 production remains substantial across Asia and the Middle East. Key supply origins:

That rationalization is structural rather than cyclical, and it hits bright stock — the heavier co-product of the same Group I plants — even harder than SN500 itself. See why bright stock and SN500 stay structurally short for what that means for marine, gear and grease buyers securing supply.

• Southeast Asia — Indonesia, Thailand and Singapore host long-established Group I refineries supplying regional blenders. Combined with Port Klang in Malaysia, the region is a primary hub for ISO tank, flexibag and bulk-vessel SN500 shipments into Vietnam, the Philippines, Bangladesh and Pakistan.
• South Korea — although Korea is best known for Group II and Group III capacity, several producers still supply Group I heavy neutrals into Southeast Asia, especially for grease and industrial-oil buyers seeking consistent SN500 supply.
• Middle East — Iran and the broader Gulf region remain significant Group I producers, with cargoes moving by vessel into India, Pakistan and East Africa. Disruptions through the Strait of Hormuz have pushed buyers to actively diversify origin.
• Malaysia — Malaysia is a strategic re-export and trading hub for Group I base oils including SN500. Cargoes are aggregated at Port Klang and dispatched by ISO tank, flexibag or bulk vessel across Asia and the Middle East — a route Sanyang Petroleum actively operates.
• Regional trade flows — Platts and Argus benchmark Group I SN500 differentials on a CFR Singapore and CFR India basis. Pricing typically tracks Brent crude with a structural lag and reflects the spread to Group II 500N at any given time.

What buyers should consider before purchasing SN500

SN500 is commoditized, but quality and supply consistency vary materially between refineries. Procurement teams evaluating offers should focus on:

• Specification consistency — verify viscosity at 40°C and 100°C, VI, flash point, pour point and color against the current TDS, and request a batch CoA before every nomination.
• Supply reliability — confirm the producing refinery, not just the trading origin. Switching refinery mid-formulation can shift color, oxidation behavior and additive response.
• Packaging options — choose between ISO tank (20–25 MT), flexibag (20–22 MT), 200L drums, IBC totes (1000L), tank truck or bulk vessel based on warehouse handling, end-use volumes and downstream packaging requirements.
• Logistics planning — review CFR vs FOB economics, port congestion at the destination and lead times. For Southeast Asian buyers, Port Klang origin typically offers shorter and more predictable voyages than Middle East cargoes routed through Hormuz.
• Technical documentation — require TDS, batch CoA, SDS (REACH/GHS compliant where applicable) and the SGS or equivalent third-party inspection report at load port.

SN500 supply from Sanyang Petroleum

Sanyang Petroleum is a Malaysia-based principal trader of industrial petroleum products serving lubricant manufacturers, industrial blenders, importers and distributors across Southeast Asia, South Asia and the Middle East. Our base oil portfolio spans Group I solvent neutrals (including SN150 and SN500), Group II 150N/500N, Group III and Group III+ base stocks, naphthenic base oils, TDAE, RPO and white oils.

We operate from Port Klang with ISO tank, flexibag, drum, tank truck and bulk vessel logistics. Every parcel is supplied with full technical documentation — TDS, batch CoA and SDS — and pricing is referenced to recognized industry benchmarks (Platts, Argus) on FOB, CFR or CIF Incoterms. As a member of Canven Group, Sanyang Petroleum maintains direct relationships with refinery-origin supply for stable long-term contracts as well as spot cargo offers.

For lighter solvent neutral demand see our SN150 product page, and for higher-performance applications evaluate Group III base oils from our portfolio.

Frequently asked questions