AMSOIL SEVERE GEAR® SAE 250 100% Synthetic Gear Lube
Use in API GL-5, hypoid gear applications that require higher-viscosity oil, including off-road race trucks, rock racers and crawlers, competition tractors, funny cars, dragsters, and heavy equipment. Where limited-slip performance is required, use AMSOIL Slip Lock limited-slip additive.
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Product data sheets
View, download, or save a copy of the Product Data Sheet or Safety Data Sheet for AMSOIL SEVERE GEAR® SAE 250 100% Synthetic Gear Lube.
AMSOIL SEVERE GEAR SAE 250 100% Synthetic Gear Lube
AMSOIL SEVERE GEAR SAE 250 (SRT) is an ultra-heavy, extreme-pressure, 100 percent synthetic API GL-5 racing gear lubricant for hypoid differentials that call for a much heavier viscosity than a typical 75W-140 or 80W-90 street gear oil. The SAE 250 grade is engineered for hard-driven drag-race rear ends, pulling-truck differentials, dirt-track rear ends, rock racers, rockcrawlers, funny cars, dragsters, and other competition or heavy-equipment applications where a tuner, builder, or chassis manufacturer specifies an extra-thick gear oil to combat shock loading, sustained high G-forces, lubricant sling-off, and ring-and-pinion contact at steep angles.
Extra-heavy film for shock loading and high-load gears
Drag rear ends, pulling-truck differentials, and competition off-road axles see brief, violent torque spikes that can punch through a thinner gear film and bring metal into contact. SEVERE GEAR SAE 250 is built on shear-stable, heavy synthetic base oils with an extra-heavy treatment of extreme-pressure additives, producing a kinematic viscosity of 46.6 cSt at 100 C and 474.8 cSt at 40 C (ASTM D445) for a thick, load-bearing film. The proprietary EP package forms an iron-sulfide barrier on gear surfaces that holds up against pitting, scoring, and adhesive wear, and the formula carries a Falex Procedure B failure load of 3,250 lbf (ASTM D3233) and a Four-Ball Wear scar of 0.40 mm (ASTM D4172, 40 kg, 75 C, 1,200 rpm, 1 hr).
Tenacious cling for high G-forces and steep pinion angles
Centrifugal force in a high-rpm rear end can sling a thinner lube clear of the ring and pinion, and a high-pinion or steeply offset axle can leave the upper teeth running on a starved film between launches. SEVERE GEAR SAE 250 is specifically engineered for high-horsepower, high-torque conditions where centrifugal sling-off is encountered. The tenacious formulation clings to gears and bearings during shock loading, sustained G-forces, and where pinion gears are installed at steep angles, helping protect ring-and-pinion sets through repeated launches and long competition runs.
Cold-pour fluidity despite the heavy SAE 250 grade
Conventional heavy gear oils carry waxes that can solidify in cool weather, leaving gears starved on the first pass through the staging lanes or at the start of an early-morning pull. SEVERE GEAR SAE 250 contains no wax and provides excellent fluidity for a grade this thick, with a pour point of -25 C (-13 F) per ASTM D97 and a 154 viscosity index (ASTM D2270). Quicker oil flow at startup means faster delivery to gears and bearings, while the high VI helps the oil hold a usable film as the rear-end housing climbs into operating temperature.
Thermal stability for sustained competition heat
Sustained drag, pulling, and off-road racing service drives differential temperatures up fast. SEVERE GEAR SAE 250 holds a flash point of 234 C (453 F) per ASTM D92, posts a 1B copper corrosion rating (ASTM D130) for compatibility with bronze and brass parts in racing axles, and resists thermal breakdown that can otherwise lead to varnish, sludge, and lost film strength under prolonged competition heat.
Built for hypoid racing differentials
Aftermarket racing rear ends from Strange, Mark Williams, Currie, Moser, Detroit Speed, quick-change manufacturers, and competition pulling and off-road axle builders frequently call for an SAE 250-class gear oil. SEVERE GEAR SAE 250 targets that requirement and is not intended for street passenger-vehicle differentials, where 75W-90 or 75W-140 SEVERE GEAR matches the OEM viscosity. Where a limited-slip carrier needs friction-modifier topping after a fluid change, add AMSOIL Slip Lock limited-slip additive at the carrier builder's recommended ratio.
Recommended applications and service intervals
SEVERE GEAR SAE 250 is built for API GL-5 hypoid gear applications that require a very high-viscosity gear lube and is intended for severe racing and equivalent service rather than daily street use. Confirm with the differential or vehicle builder, then apply where the following conditions match:
API GL-5 hypoid gear applications that specifically call for an SAE 250 viscosity, including off-road race trucks, rock racers and crawlers, competition pulling tractors, funny cars, dragsters, and heavy-duty trucks and equipment that need an extra-thick film.
Limited-slip carriers: pair with AMSOIL Slip Lock limited-slip additive at the carrier builder's specified ratio to restore friction modification after a drain.
Not recommended where the vehicle or differential builder calls out a different viscosity grade. For passenger-car, light-truck, and tow-rated applications, match the OEM viscosity using SEVERE GEAR 75W-90, 75W-110, 75W-140, or 80W-90.
Outside the United States and Canada, follow the differential builder or chassis manufacturer's grade recommendation and match the right product with the AMSOIL Vehicle Lookup Guide.
SEVERE GEAR SAE 250 is intended for severe racing and other applications where extended drain intervals are not beneficial. Change the lube as conditions dictate, and extend drain intervals only as recommended by oil analysis. The formula is compatible with synthetic and conventional automotive gear oils, but mixing with other gear oils shortens oil life and reduces performance benefits. Aftermarket oil additives, other than AMSOIL Slip Lock where limited-slip performance is required, are not recommended for use with AMSOIL gear oil.
Order SEVERE GEAR SAE 250 Synthetic Racing Gear Lube
SEVERE GEAR SAE 250 is available in quart bottle (SRTQT-EA), case of 12 quarts (SRTQT-CA), 5 gallon pail (SRT05-EA), and 55 gallon drum (SRT55-EA). All AMSOIL gear lubricants are backed by the AMSOIL Limited Warranty. Confirm the differential build and recommended viscosity with the AMSOIL Vehicle Lookup Guide, compare against the street-grade options in the AMSOIL 75W-90 Gear Oil Guide, then order AMSOIL SEVERE GEAR SAE 250 100% Synthetic Gear Lube.
used this in a 2016 TRD 4x4 Tundra 5.7 Supercharged 100,000 miles on the motor There are a number of other things I have done to the Engine,Exhaust, suppression. I have used other Amsoil product in the gear box on my 2016 Tundra with no problem. I just wanted to try the new SAE 250 I also used this product in my transfer case. The one thing I noticed is both front & Rear differential along with the Transfer case are a lot quitter. And by the way anything the gear grease touch it won't come off. Thank you Amsoil
By Duane from Oklahoma on April 23, 2023.
Would recommend this to a friend.
Good Stuff
I've used Amsoil Severe Gear in race cars for a long time and have never had a failure due to lubrication (and believe that this product has actually made differentials last longer than standard lubes would have). So, when the differential in my Kia Sorento began humming a tune I figured that Severe Gear might help make the costly repair a little further off in the future. It's been a couple of months now and the noise had dramatically diminished. I'm confident that my differential's life has been extended...maybe even saved.
What is SAE 250 gear oil and how does it compare to 75W-140 or 80W-90?
SAE 250 is an extra-heavy gear oil grade considerably thicker than the 75W-140 and 80W-90 viscosities used in most street and tow-rated rear ends. SEVERE GEAR SAE 250 measures 46.6 cSt at 100 C and 474.8 cSt at 40 C (ASTM D445), which is well above a typical 75W-140 and is intended for racing and competition rear ends specifically built or specified for an SAE 250-class lubricant. For passenger-car, light-truck, and tow service, use the OEM-spec 75W-90, 75W-110, 75W-140, or 80W-90 grade in the SEVERE GEAR family.
Is this the right gear oil for a drag-race rear end like Strange, Mark Williams, Currie, Moser, or Detroit Speed?
Many drag-race rear-end builders call for an SAE 250-class gear oil to handle launch loads and sustained heat. SEVERE GEAR SAE 250 is engineered for that role and clings to ring-and-pinion gears under shock loading. Confirm the exact viscosity with the rear-end manufacturer and any limited-slip carrier supplier before service.
Can SAE 250 gear oil be used in a daily-driven truck or street car?
No. SEVERE GEAR SAE 250 is intended for severe racing and equivalent applications where the differential or vehicle builder specifies an extra-heavy grade. For daily-driven trucks, towing, off-road overland use, and street applications, match the OEM viscosity using SEVERE GEAR 75W-90, 75W-110, 75W-140, or 80W-90.
Does SEVERE GEAR SAE 250 need a friction modifier for limited-slip differentials?
Where limited-slip performance is required, add AMSOIL Slip Lock limited-slip additive at the carrier builder's specified ratio. Slip Lock restores friction-modifier balance after a fluid change and quiets clutch chatter in clutch-type limited-slip carriers.
How often should the rear-end gear oil be changed in a race vehicle?
SEVERE GEAR SAE 250 is intended for severe racing and other applications where extended drain intervals are not beneficial. Change the gear lube as conditions dictate, based on race day count, ambient and operating temperatures, and any signs of contamination on the magnet or in the drain sample. Extend drain intervals only as recommended by used-oil analysis.
Is this oil compatible with other gear oils already in the differential?
The formula is compatible with synthetic and conventional automotive gear oils, but mixing shortens oil life and reduces performance benefits. Aftermarket oil additives, other than AMSOIL Slip Lock where limited-slip performance is required, are not recommended. Drain the existing fluid completely before refilling.
