OS Giken 80W-250 Gear Oil – 1 Litre | Ultra-High Viscosity Competition Gear & Differential Oil

The OS Giken 80W-250 Gear Oil is an ultra-high viscosity competition gear oil engineered specifically for OS Giken limited slip differentials and competition differential applications — where the extreme contact pressures, high operating temperatures, and demanding friction requirements of OS Giken's LSD clutch pack systems demand a gear oil formulated to a specification that standard 75W-90 and 75W-140 gear oils cannot meet. This listing is for a single 1 litre bottle. Also available in a case of 6 x 1L for bulk purchasing. The 80W-250 viscosity grade is exceptionally high — significantly thicker at operating temperature than even the 75W-140 grade used in demanding performance applications — providing the extreme-pressure oil film thickness that OS Giken's high-performance LSD units require for correct clutch pack operation, gear protection, and long-term reliability under competition loads.

Key Features:

• Single 1 litre bottle — correct for a single differential service or topping up an OS Giken LSD unit — also available in a case of 6 x 1L for bulk purchasing
• 80W-250 ultra-high viscosity — exceptionally high viscosity grade engineered for the extreme contact pressures and operating temperatures of OS Giken LSD and competition differential applications — significantly thicker at operating temperature than 75W-140 alternatives
• OS Giken LSD specific — formulated for the friction and viscosity requirements of OS Giken's limited slip differential clutch pack systems — correct oil for OS Giken LSD units
• Extreme pressure protection — ultra-high viscosity provides maximum oil film thickness under the extreme contact pressures generated by OS Giken LSD clutch packs and hypoid gear sets under competition loads
• Competition grade — engineered for the demands of motorsport and competition use where standard gear oils are insufficient for the loads and temperatures generated
• OS Giken quality — manufactured by OS Giken, one of Japan's most respected high-performance differential and engine component brands

Why 80W-250? Understanding the Viscosity Grade:

• Standard Gear Oil Viscosity Grades: Most performance differentials specify 75W-90 or 75W-140 gear oil — viscosity grades that provide adequate film strength for standard hypoid differential gear sets and most LSD clutch pack designs. The 75W-140 grade is considered a high-viscosity option for demanding applications.
• OS Giken LSD Requirements: OS Giken's limited slip differentials are high-performance, high-engagement LSD units engineered for motorsport and serious performance applications — with clutch pack designs and engagement characteristics that generate significantly higher contact pressures and operating temperatures than standard LSD units. These extreme conditions require a gear oil with a viscosity grade that provides adequate film thickness under loads that would cause a 75W-140 oil to thin beyond its effective protection range. The 80W-250 grade provides the additional film thickness required.
• Clutch Pack Friction Characteristics: OS Giken LSD units have specific friction requirements for correct clutch pack engagement and release behaviour. Using a gear oil with incorrect viscosity or friction characteristics can cause incorrect LSD engagement, clutch pack chatter, or premature clutch pack wear. The OS Giken 80W-250 is formulated with the correct friction characteristics for OS Giken's clutch pack design — ensuring correct LSD behaviour and clutch pack longevity.
• Do Not Substitute: Using a lower-viscosity gear oil (75W-90, 75W-140) in an OS Giken LSD that specifies 80W-250 will result in insufficient film thickness under competition loads — potentially causing accelerated gear and clutch pack wear. Always use the manufacturer-specified oil for OS Giken LSD units.

Specifications:

• Brand: OS Giken
• Part Number: OSGOS011-KA1
• Barcode: OS011-KA1
• Viscosity Grade: 80W-250
• Volume: 1 litre (single bottle)
• Application: OS Giken LSD units and competition differentials specifying 80W-250 gear oil

Recommended Applications:

• OS Giken limited slip differentials specifying 80W-250 gear oil — verify the correct oil specification for your specific OS Giken LSD model in OS Giken's product documentation
• Single differential service or top-up — OS Giken LSD units typically require 0.5–1.0 litres per differential depending on the housing
• Competition differentials and gear sets operating under extreme contact pressures and elevated temperatures where standard 75W-90 and 75W-140 gear oils are insufficient
• Motorsport applications — circuit racing, time attack, rally, and drag racing — where drivetrain reliability under extreme loads is critical

Usage Notes:

• Verify the correct oil specification for your specific OS Giken LSD model before use — OS Giken produces multiple LSD models with different oil specifications. Confirm that 80W-250 is the correct specification for your specific unit in OS Giken's product documentation or by contacting Straight Six Imports.
• OS Giken LSD units typically require 0.5–1.0 litres per differential depending on the housing — verify your specific unit's fluid capacity before ordering to ensure you purchase the correct quantity. Order multiple bottles if required.
• Follow OS Giken's recommended fluid change interval for your LSD unit — competition use typically requires more frequent fluid changes than street use due to elevated operating temperatures and clutch pack wear debris accumulation
• Drain the old fluid completely and flush the differential before refilling with fresh OS Giken 80W-250 — mixing old and new fluid reduces the effectiveness of the fresh oil

Why OS Giken?

OS Giken is one of Japan's most respected high-performance differential and engine component brands — known for their Super Lock LSD differentials, close-ratio gearboxes, and engine components used in professional motorsport and serious performance applications across Japan and internationally. OS Giken's LSD units are among the most highly regarded limited slip differentials available for Japanese performance platforms — used by professional racing teams and serious performance drivers who demand the highest level of differential performance and reliability. OS Giken's 80W-250 gear oil is formulated specifically for their LSD units — the correct oil from the brand that built the differential, engineered to the exact viscosity and friction specifications that OS Giken's clutch pack designs require.

Perfect For:

• OS Giken LSD owners who want the correct, manufacturer-specified 80W-250 gear oil for a single differential service or top-up
• Competition and motorsport builds running OS Giken LSD units where correct differential fluid specification is critical for clutch pack longevity and LSD performance
• Differential fluid service on OS Giken LSD units after track sessions, competition events, or at the manufacturer's recommended change interval

Critical Note: Single 1 litre bottle — verify your OS Giken LSD's fluid capacity and order the correct quantity. Verify that 80W-250 is the correct oil specification for your specific OS Giken LSD model before use — consult OS Giken's product documentation or contact Straight Six Imports. Do not substitute lower-viscosity gear oils. Follow OS Giken's recommended fluid change interval.