10W-30 is the fast-growing fuel-economy heavy-duty diesel grade in India — specified by Tata, Ashok Leyland, BharatBenz, Volvo, and most BS-VI heavy-truck OEMs as the modern replacement for 15W-40. It also serves as a multi-fleet dual-claim CK-4 / SN oil for mixed truck-and-petrol-car operations. This guide walks through the realistic composition of a 10W-30 CK-4 formulation — Group II base oil, OCP viscosity modifier, low-SAPS DI package, ZDDP chemistry, and the four-step manufacturing process with BIS IS 13656 pass targets.
The “10W-30” designation comes from SAE J300, the Society of Automotive Engineers viscosity classification for engine oils. It is a fuel-economy multigrade — lighter than 15W-40 at both ends, designed to reduce viscous drag in modern emissions-friendly engines.
10W is the winter rating — it commits the oil to a maximum cold-crank simulator viscosity of 7,000 cP at −25 °C (ASTM D5293) and pumpability at −30 °C (ASTM D4684 MRV 60,000 cP max). This is materially better than 15W (which is rated at −20 °C cranking, −25 °C pumping).
30 is the high-temperature rating — KV100 between 9.3 and 12.5 cSt (ASTM D445) and HTHS of 2.9 cP minimum at 150 °C (ASTM D5481). For API CK-4 the HTHS commitment goes up to 3.5 cP minimum — this is a heavy-duty diesel category requirement, not an SAE J300 rule.
A 10W-30 sits in the technical sweet spot between 15W-40 (workhorse but viscous) and 5W-30 (premium and expensive). It can be formulated on Group II base oil (rather than the Group III required for 5W-30), keeping it affordable while delivering measurable fuel-economy gains in heavy-duty fleet operation.
| Component | Function | Typical % (m/m) | Notes |
|---|---|---|---|
| Base oil — Group II 4 cSt | Light-cut backbone — cold-crank and viscosity | 35–45% | Chevron 110N / IOCL Yubase G2 4 / Neste Nexbase 2004 |
| Base oil — Group II 6 cSt | Mid-cut backbone — KV100 contribution | 35–45% | Chevron 220R / IOCL Yubase G2 6 |
| VII — OCP polymer (10–12% active) | Viscosity index improvement; lower load than 5W-30 | 6–8% | OCP standard; Group II base needs less VII than Group III |
| Low-SAPS DI package (CK-4) | Detergent + dispersant + ZDDP + antioxidant + CI | 11–12.5% | Lubrizol LZ8910, Infineum D3525, Oronite OLOA 49100 |
| Overbased Ca sulfonate (component) | Detergent — deposit control, TBN reserve | 2.5–3.5% | TBN target 9 mgKOH/g for CK-4 |
| Calcium / Magnesium phenate | Antioxidant detergent — high-temp deposit control | 1.0–1.8% | Mg phenate is increasingly used in CK-4 for LSPI mitigation in dual-claim formulations |
| PIBSI dispersant | Soot dispersion, sludge control | 4–5.5% | Heavy dose — CK-4 demands 7%+ soot handling |
| Secondary alkyl ZDDP | Antiwear, antioxidant; thermal stability | 0.8–1.1% | Delivers 0.10–0.12% P (CK-4 limit 0.12% max) |
| Alkylated diphenylamine (ADPA) | Primary antioxidant — CK-4 demands strong oxidation | 0.5–1.0% | Significantly higher than 15W-40 CI-4 to compensate for reduced ZDDP |
| Pour point depressant (PMA) | Lowers pour point of Group II base oil blend | 0.15–0.3% | Standard PMA |
| Silicone defoamer | Suppresses foaming during operation | 5–15 ppm | Dilute before addition |
10W-30 in CK-4 is generally formulated with a commercial CK-4 DI package because of the demanding heavy-duty engine test slate — Caterpillar 1N, Mack T-11, Mack T-13, Volvo D13. Component blending is rare and only economical at very high volume.
| Property | API CJ-4 | API CK-4 | API FA-4 | SN / SP (petrol only) |
|---|---|---|---|---|
| Target engines | BS-IV diesel + EGR | BS-VI diesel + DPF/SCR | BS-VI fuel-economy diesel | BS-VI petrol PCMO |
| HTHS @ 150 °C | 3.5 cP min | 3.5 cP min | 2.9–3.2 cP | 2.9 cP min |
| Phosphorus (D5185) | 0.12% max | 0.12% max | 0.12% max | 0.08% max |
| Sulphated ash (D874) | 1.0% max | 1.0% max | 1.0% max | 0.9–1.1% |
| Sulphur | 0.4% max | 0.4% max | 0.3% max | 0.4% max |
| NOACK volatility | 13% max | 13% max | 12% max | 13% max |
| Oxidation stability (Volvo T-13) | Required | Required (enhanced) | Required (enhanced) | Not required |
| Aftertreatment compatibility | DPF + SCR | DPF + SCR (BS-VI) | DPF + SCR + FE | TWC |
| Typical DI pack treat rate | 11–12% | 11–12.5% | 11–12.5% | 10–11.5% |
| Indicative cost premium vs CJ-4 | Baseline | +Rs 5–12 / L | +Rs 8–15 / L | Different formula |
CK-4 is backward compatible to CJ-4 / CI-4 / CH-4 — a CK-4 10W-30 can replace older categories without OEM concern. FA-4 is a separate fuel-economy category not backward compatible (lower HTHS) — only used where specifically approved. Dual-claim CK-4 + SN demands both Mack T-13 and Sequence VIII engine test passes.
| Property | ASTM Method | IS 13656 HD-3 Limit | Recommended Formulation Target |
|---|---|---|---|
| KV @ 100 °C | D445 | 9.3–12.5 cSt | 11.2–11.8 cSt |
| KV @ 40 °C | D445 | Report | 68–76 cSt |
| Viscosity Index | D2270 | 135 min | 142–152 |
| CCS @ −25 °C | D5293 | 7,000 cP max | 5,500–6,300 cP |
| MRV @ −30 °C | D4684 | 60,000 cP max | 28,000–42,000 cP |
| HTHS @ 150 °C | D4683 | 3.5 cP min (CK-4) | 3.6–3.8 cP |
| Pour point | D97 | −24 °C max | −33 to −39 °C |
| Flash point (COC) | D92 | 200 °C min | 225–238 °C |
| TBN | D2896 | 7 mgKOH/g min | 9–10 mgKOH/g |
| Sulphated ash | D874 | 1.0% max | 0.88–0.96% |
| NOACK volatility | D5800 | 13% max | 9–11% |
| Four-ball wear scar | D4172 | 0.6 mm max | 0.42–0.50 mm |
The HD-3 designation in IS 13656 covers heavy-duty diesel multigrade — the right BIS category for 10W-30 CK-4. The 0.88–0.96% sulphated ash target leaves a 4–12% margin against the 1.0% CK-4 ceiling, protecting against batch variation. See our BIS IS 13656 process guide for the full submission procedure.
10W-30 is most commonly a heavy-duty diesel oil (HDMO) — API CK-4 is the dominant claim, used for modern BS-VI commercial diesel with DPF and SCR. It also exists as a dual-claim CK-4 / SN multi-fleet product for mixed truck-and-passenger-car fleets, and as a standalone SN / SP petrol PCMO in some markets, but in India the HDMO position is dominant by volume — roughly 4:1 HDMO to petrol PCMO for 10W-30.
OEMs (Tata, Ashok Leyland, Volvo, BharatBenz, Daimler) have been shifting BS-VI heavy-duty diesel factory fill from 15W-40 to 10W-30 for fuel-economy. 10W-30 delivers 1.5 to 3% better fuel economy than 15W-40 because of lower HTHS (3.5 cP versus 3.9+) and lower base viscosity at operating temperature. This is the same fuel-economy logic that pushed petrol PCMO from 15W-40 to 5W-30 a decade earlier — HDMO is catching up.
For API CK-4 the ZDDP treat rate is 0.8 to 1.1% delivering 0.10 to 0.12% phosphorus (CK-4 P limit is 0.12% max). Sulphated ash is capped at 1.0% (low-SAPS). The ZDDP reduction versus CI-4 / CI-4 Plus (which ran 1.1–1.4% ZDDP) is balanced with additional ADPA antioxidant (0.5–1.0%) and richer dispersancy to maintain wear and soot performance through the longer drain.
Marginal for CK-4 but possible for older CI-4 / SN claims. The CCS limit at −25 °C (7,000 cP max) is comfortably met by Group I but the NOACK volatility limit of 13% for SP and CK-4 is hard to clear with Group I (typical NOACK 18–25%). Group II is the workhorse base for 10W-30 in India; Group II+ or Group III/II blend is preferred for CK-4 dual-claim with SP because the volatility margin is tighter.
For API CK-4 / FA-4 the HTHS target depends on the claim — CK-4 demands 3.5 cP min, FA-4 demands 2.9–3.2 cP (the fuel-economy heavy-duty grade). For a dual-claim CK-4 / SN petrol multi-fleet, the practical design target is HTHS 3.5 to 3.7 cP. For petrol-only SN / SP claim the floor is 2.9. Aim for at least a 0.1 cP margin above the floor to absorb batch variation.
Direct material cost for an API CK-4 10W-30 ranges from Rs 145 to 175 per litre at current Group II base oil and additive prices. SN / SP petrol-only 10W-30 runs Rs 130 to 160. Dual-claim CK-4 / SN runs Rs 160 to 195 because of the richer DI pack needed to clear both diesel soot and petrol LSPI tests. Add Rs 7 to 12 per litre for packaging, labour, utilities, and overhead.
For BS-IV and BS-VI engines, yes — OEMs increasingly approve 10W-30 in vehicles originally specified for 15W-40. For pre-BS-IV engines (BS-II / BS-III), 15W-40 remains the workshop default because the older bearing and ring clearances were designed around 15W-40 HTHS and 40-grade viscous protection. Going below the OEM-specified viscosity in old worn engines can increase oil consumption.
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