Marine Lubricant Guide

Marine Gear Oils — Reduction Gears & Deck Gear

Marine gear oils protect the heavily loaded tooth contacts of main reduction gears, deck machinery drives and enclosed gearboxes. Extreme-pressure performance, the correct viscosity and clean, dry oil are what keep gear sets running to their design life.

Key Specifications

Application
Reduction gears, deck gear, enclosed drives
Viscosity
ISO VG 100–320 (SAE 90 equiv.)
Additive system
Extreme-pressure (EP)
Typical Use

Main propulsion reduction gearboxes, deck-crane and winch gearing, and general enclosed industrial gear drives aboard ship.

Technical Detail

Extreme-pressure load carrying

Gear teeth operate under high sliding and rolling loads. EP additives form a protective film that prevents scuffing and welding at the tooth contact. The oil must carry these loads without harming the bronze and steel components in the gear train.

Viscosity and micropitting

Viscosity grade is set by the gear's speed, load and operating temperature — too thin and the film breaks down, too thick and churning losses and heat rise. Modern gear oils are also formulated to resist micropitting, a fatigue mode that roughens tooth flanks over time.

Water and cleanliness control

Water contamination sharply reduces gear-oil load capacity and promotes rust. Good demulsibility, filtration and regular oil analysis (viscosity, water, wear metals, additive level) protect the gear set between changes.

Ports Where We Supply Marine Gear Oil

Seven Ocean procures and delivers Marine Gear Oil alongside bunker fuel at every major bunkering hub worldwide and across all 25 Indian ports — matched to your engine maker's approvals. Select a port for its full bunkering guide.

International Hubs

Indian Ports

Frequently Asked Questions

What viscosity gear oil does my gearbox need?

Use the gear maker's specified ISO VG. Marine reduction gears commonly run VG 100–220; heavily loaded or slow gearing may call for VG 320. We match the approved grade to your unit.

Are EP additives safe for yellow-metal components?

Modern marine EP gear oils are formulated to be compatible with the bronze and brass found in marine gears. Where yellow metals are sensitive, we can supply a suitably mild-EP or R&O grade.

Can one oil serve both the main gear and deck gear?

Sometimes, but the ratings differ. It's usually better to match each drive to its recommended grade; we can consolidate where the specifications genuinely overlap.

Need a marine lubricant quote?

Seven Ocean supplies engine, system and machinery lubricants at every major global hub — matched to your engine maker's approvals. Tell us the vessel, the port, and the grade, and we'll come back with an offer.

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