Extended-drain lubricant engineered to last longer and protect gears better than conventional gear oils. Reduces wear, conditions seals, and helps prevent rust. Promotes longer equipment life and reduced maintenance costs.
Add an AMSOIL Preferred Customer membership to the same cart to unlock up to 25% off qualifying products. Existing members can sign in, and qualifying orders currently over $100 can ship free.
Product data sheets
View, download, or save a copy of the Product Data Sheet or Safety Data Sheet for AMSOIL 80W-140 Long Life 100% Synthetic Gear Lube.
AMSOIL 80W-140 Long-Life 100% Synthetic Gear Lube (FGO) is the heavy-viscosity, extended-drain fleet gear oil engineered for 500,000-mile (805,000 km) service life in over-the-road Class 8 trucks, drive axles, and heavy-haul drivelines that operate in hot climates and high-load duty cycles. Built on premium synthetic base oils with a high-performance additive system, the formula meets API GL-5 and MT-1, MIL-PRF-2105E, and heavy-duty fleet axle approvals from Dana, Mack, Meritor, and ZF. It is the heavy-grade companion to AMSOIL 75W-90 Long-Life Synthetic Gear Lube, sized for the higher operating temperatures and gear-tooth loads typical of fleet rear axles in warm regions and severe haul.
Long service life in heavy-duty fleet axles
Premium synthetic base oils and a high-performance additive package resist oxidative breakdown so the lubricant stays in service longer than conventional 80W-140 and 85W-140 gear oils. The 80W-140 grade supports extended drain intervals up to 500,000 miles (805,000 km) on the OEM schedule for over-the-road trucks and heavy equipment, and lasts several times longer than conventional lubricants for less downtime and lower maintenance cost.
High-load gear and bearing wear protection
A shear-stable formulation resists viscosity loss from mechanical activity, so the oil holds its working film thickness across long pulls, heavy hauls, and high gear-tooth loads in hypoid drive axles. Anti-wear and extreme-pressure additives resist chemical breakdown for long-lasting protection of ring-and-pinion sets and bearings. The 80W-140 viscosity, at 26.3 cSt at 100 C and 244.8 cSt at 40 C (ASTM D445), gives the additional oil-film thickness that hot, heavy fleet differentials and tow rigs benefit from in severe duty.
Hot-climate viscosity stability and high-temperature performance
A flash point of 216 C (421 F) per ASTM D92 and a viscosity index of 138 per ASTM D2270 keep the lubricant film stable at the elevated sump temperatures that develop in long-haul fleet axles and hot-climate operation. The shear-stable formula holds the 80W-140 grade across long drains rather than thinning under mechanical stress, so protection holds at the back end of a 500,000-mile service interval. A 1B rating in the Copper Strip Corrosion Test (ASTM D130) at 121 C for 3 hours and 0/0, 0/0, 0/0 foam control per ASTM D892 round out the high-temperature profile.
Cold-temperature fluidity and seal compatibility
Even at the heavier 80W-140 grade, the synthetic formulation pours to -43 C (-45 F) and holds a Brookfield viscosity of 63,706 cP at -26 C (ASTM D2983), so the oil flows to gears and bearings at startup instead of leaving a frozen lube in the housing. The additive system resists acid build-up to keep gear surfaces clean over long drains, and the formula conditions seals to help prevent leaks while supporting rust and corrosion protection for equipment that sees humid climates or wet operating environments.
Recommended applications and service intervals
The 80W-140 grade is recommended for over-the-road trucks, light, medium, and heavy-duty trucks, off-road equipment, commercial vehicles, motorhomes, autos, SUVs, emergency vehicles, buses, delivery and utility vehicles, and tractors, plus differentials, manual transmissions, and other gear applications that call for the listed standards.
Cars, SUVs, and light trucks: drain at 100,000 miles of service or according to the owner's manual under normal service, and 50,000 miles or owner's manual under severe service, whichever is longer.
Heavy-Duty Class 8 line haul: follow the OEM drain interval (miles or hours) up to 500,000 miles or five years, whichever comes first.
Vocational and delivery: follow the OEM drain interval (miles or hours) for synthetic oil up to 120,000 miles or three years, whichever comes first. Heavy-duty off-road: follow the OEM drain interval (miles or hours) for synthetic oil up to 100,000 miles or two years, whichever comes first.
For non-differential applications, use the OEM normal or severe synthetic-oil service interval. Where service intervals are unavailable, drain at twice the conventional-oil interval. Extended drain intervals are not supported where water contamination occurs, and gear oils should be changed more frequently in dusty or dirty conditions unless the gear system is properly sealed and equipped with membrane-type breathers.
The 80W-140 grade replaces competitors' 80W-140 and 85W-140 viscosity grades and is compatible with other synthetic and conventional gear oils, although mixing shortens oil life, reduces performance benefits, and voids the extended-drain claim. The formula is compatible with most limited-slip differentials; if limited-slip chatter occurs, add AMSOIL Slip-Lock friction modifier additive.
Typical technical properties
Property
Value
Kinematic Viscosity at 100 C, cSt (ASTM D445)
26.3
Kinematic Viscosity at 40 C, cSt (ASTM D445)
244.8
Viscosity Index (ASTM D2270)
138
Brookfield Viscosity, cP at -26 C (ASTM D2983)
63,706
Flash Point, C (F) (ASTM D92)
216 (421)
Pour Point, C (F) (ASTM D97)
-43 (-45)
Copper Strip Corrosion at 121 C / 3 hr (ASTM D130)
1B
Foam Stability (ASTM D892)
0/0, 0/0, 0/0
Order AMSOIL 80W-140 Long-Life Synthetic Gear Lube
AMSOIL 80W-140 Long-Life Synthetic Gear Lube is available in 5-gallon pail (FGO05-EA), 55-gallon drum (FGO55-EA), and 275-gallon tote (FGO27-EA). Using AMSOIL synthetic lubricants and practicing extended drain intervals does not void a new vehicle or equipment manufacturer warranty, and AMSOIL products are backed by the AMSOIL Limited Warranty. Match the right product with the AMSOIL Vehicle Lookup Guide, compare grades and OEM specs in the AMSOIL 75W-90 Gear Oil Guide, then order AMSOIL 80W-140 Long-Life 100% Synthetic Gear Lube.
What is the difference between AMSOIL 80W-140 Long-Life Gear Lube (FGO) and 75W-90 Long-Life (FGR)?
FGO is the heavy-viscosity 80W-140 grade for heavy-haul fleet axles, hot-climate operation, and applications that call for an 80W-140 or 85W-140 gear oil. FGR is the lighter 75W-90 grade for cold-weather and standard-climate fleet axles where an 85W-90 or 75W-90 is specified. Both meet API GL-5 and MT-1, share the same Dana, Mack, Meritor, and ZF heavy-duty axle approvals, and support up to 500,000-mile Class 8 line-haul drain intervals on the OEM schedule.
What is the difference between FGO 80W-140 and Severe Gear 75W-140 (SVO)?
FGO 80W-140 Long-Life is the heavy-duty fleet, over-the-road, and extended-drain heavy-grade engineered for Class 8 line-haul axles and built around heavy-duty fleet axle approvals. Severe Gear 75W-140 is the passenger and light-truck severe-service heavy-grade for towing, hauling, plowing, racing, and high-temperature differential use. Both meet API GL-5, but FGO is the right choice for heavy-duty fleet drive axles and trailer axles where long fleet drain intervals and heavy-haul gear-tooth loading are the primary duty.
Which OEM specifications and standards does the 80W-140 grade meet?
The 80W-140 grade meets API GL-5 and MT-1, MIL-PRF-2105E, Dana SHAES 234 (formerly Eaton PS-037) for 250,000 miles, Dana SHAES 256 (formerly Eaton PS-163) for 500,000 miles, Dana SHAES 429A, Mack GO-J and GO-J+, Meritor 0-80 (80W-140), plus hypoid gear oil specifications from ZF TE-ML 07A and 08, and foreign and domestic OEMs including GM, Ford, and Daimler Chrysler. It can also be used in rear axles where an API GL-4 lubricant is recommended.
How long can the 80W-140 stay in service?
In Heavy-Duty Class 8 line-haul service, drain at the OEM interval (miles or hours) up to 500,000 miles or five years, whichever comes first. In vocational and delivery service, drain at the OEM synthetic-oil interval up to 120,000 miles or three years. Heavy-duty off-road service is capped at 100,000 miles or two years on the OEM synthetic-oil interval. Cars, SUVs, and light trucks drain at 100,000 miles in normal service or 50,000 miles in severe service, or per the owner's manual, whichever is longer. Extended drain intervals are not supported where water contamination occurs.
Can the 80W-140 replace an 85W-140 conventional gear oil?
Yes. The 80W-140 Long-Life Synthetic Gear Lube replaces competitors' 80W-140 and 85W-140 viscosity grades, keeping cold-temperature fluidity for startup plus high-temperature stability for long pulls and hot-climate operation in a single grade.
Is the 80W-140 compatible with limited-slip differentials?
Yes, with most limited-slip differentials. If limited-slip chatter occurs after a fluid change, add AMSOIL Slip-Lock friction modifier additive to restore the friction characteristics required by the clutch packs.
Will running this gear lube void a heavy-duty truck or axle warranty?
No. Using AMSOIL synthetic lubricants and the listed drain intervals does not void a vehicle or equipment manufacturer warranty, and the product is backed by the AMSOIL Limited Warranty. Mixing with other gear oils will shorten oil life and the extended-drain claim is not supported when oils have been mixed.
