AMSOIL Extended-Life 10W-40 100% Synthetic Motor Oil
AMSOIL Extended-Life 100% Synthetic Motor Oil is overbuilt for road warriors so you can confidently drive up to 20,000 miles or one year, whichever comes first, between oil changes. A proprietary combination of advanced synthetic base oils and a boosted additive package promotes cleanliness and prolonged engine life. AMSOIL Extended-Life protection delivers peace of mind and convenience.
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Product data sheets
View, download, or save a copy of the Product Data Sheet or Safety Data Sheet for AMSOIL Extended-Life 10W-40 100% Synthetic Motor Oil.
AMSOIL Extended-Life 10W-40 100% Synthetic Motor Oil
AMSOIL Extended-Life 10W-40 100% Synthetic Motor Oil is a fully synthetic gasoline engine oil built for road warriors who want a long drain interval with strong wear, deposit, and LSPI protection. The XLO formula targets engines that specifically call for an SAE 10W-40 viscosity grade, a common service grade for older, higher-mileage, and heavy-duty gasoline passenger cars and light trucks. The oil meets API SQ, API SP, API SN Plus, ACEA A3/B3, and ACEA A3/B4 service categories.
Twenty-thousand-mile drain capability
Extended-Life 10W-40 is overbuilt to support normal-service drain intervals of up to 20,000 miles (32,000 km) or one year, whichever comes first, in personal vehicles operating outside severe service. Severe-service intervals run up to 12,000 miles (20,000 km) or one year, covering commercial and fleet duty, excessive idling, frequent towing, hauling, plowing, and dusty environments. The advanced synthetic base oils and a boosted additive package combine to keep the oil chemically stable through long stop-and-go service.
Resists oil breakdown under high heat
Some oils thicken or break down after extended high-temperature operation, leading to excessive consumption, deposits, accelerated wear, and difficult cold starts. Extended-Life 10W-40 holds its fluidity and viscosity under extreme conditions. The kinematic viscosity at 100 C measures 15.4 cSt by ASTM D445, the High-Temperature High-Shear viscosity at 150 C measures 4.6 cP by ASTM D5481, and NOACK volatility comes in at 5.2 percent weight loss by ASTM D5800, indicating low evaporative loss and reduced makeup oil over long drains.
LSPI defense for turbocharged direct-injection engines
Low-speed pre-ignition is the spontaneous ignition of the fuel and air mixture before the spark fires, and the event is most damaging in turbocharged gasoline direct-injection engines, where it can destroy pistons and connecting rods. Extended-Life 10W-40 carries unique chemistry formulated to guard against the event. The detergent and dispersant system also neutralizes acids and resists sludge, corrosion, and carbon deposits across the full drain interval.
Thirty-seven percent more cleaning power
Engine cleanliness directly affects ring sealing, oil-control ring function, and oil consumption in higher-mileage engines. Extended-Life 10W-40 delivers 37 percent more cleaning power than AMSOIL OE Synthetic Motor Oil, helping the engine run smoother for longer. The fortified detergent and dispersant additive package neutralizes acids and prevents sludge, corrosion, and carbon deposits, supporting the extended drain interval and the long-term cleanliness of pistons, valves, and oil passages.
Strong wear protection and viscosity stability
The 10W-40 grade gives a thicker high-temperature film than 10W-30, an advantage in older engines with wider bearing clearances and in heavy-duty gasoline service. The XLO formula posts a viscosity index of 158 by ASTM D2270, a flash point of 240 C by ASTM D92, and a pour point of -39 C by ASTM D97, supporting a wide service temperature range. The total base number of 10.7 by ASTM D2896 supports acid neutralization across long drain periods.
Recommended applications and service intervals
Extended-Life 10W-40 is built for engines that specify an SAE 10W-40 viscosity grade and that require API SQ, API SP, API SN Plus, ACEA A3/B3, or ACEA A3/B4. The 10W-40 grade is commonly listed for older domestic and Asian gasoline passenger cars, light-duty trucks, and certain higher-mileage applications. The owner manual should list one of these service categories before the oil is used.
Normal service: up to 20,000 miles (32,000 km) or one year, whichever comes first, in personal vehicles not operating under severe service.
Severe service: up to 12,000 miles (20,000 km) or one year, whichever comes first. Severe conditions include commercial and fleet duty, excessive idling, frequent towing, hauling, plowing, and dusty environments.
Modified engines, racing vehicles, and engines running alternative fuels such as E85, CNG, or propane are excluded from extended drain interval recommendations.
Outside the United States and Canada, follow the vehicle manufacturer recommended drain interval.
AMSOIL Oil Filters are designed for extended drain intervals. With other-brand filters, the interval should not exceed 12,000 miles (20,000 km) or one year unless the vehicle manufacturer recommends a longer interval. The filter should always be changed when the oil is changed, and the oil level should be checked regularly. Extended-Life 10W-40 is compatible with conventional and other synthetic motor oils, but mixing shortens the life expectancy of the oil and reduces performance benefits, and extended drain intervals are not supported when oils have been mixed. Aftermarket oil additives are not recommended for use with AMSOIL Extended-Life Synthetic Motor Oil.
Typical technical properties
Property
Value
Kinematic Viscosity at 100 C, cSt (ASTM D445)
15.4
Kinematic Viscosity at 40 C, cSt (ASTM D445)
102.9
Viscosity Index (ASTM D2270)
158
CCS Viscosity, cP at -25 C (ASTM D5293)
6047
Flash Point, C (F) (ASTM D92)
240 (464)
Fire Point, C (F) (ASTM D92)
260 (500)
Pour Point, C (F) (ASTM D97)
-39 (-38)
NOACK Volatility, percent weight loss (ASTM D5800)
5.2
High-Temperature High-Shear Viscosity at 150 C, cP (ASTM D5481)
4.6
Total Base Number (ASTM D2896)
10.7
Order Extended-Life 10W-40
Extended-Life 10W-40 is available in a quart bottle (product code XLOQT-EA), a case of 12 quarts (XLOQT-CA), a gallon jug (XLO1G-EA), a case of 4 gallon jugs (XLO1G-CA), a 55 gallon drum (XLO55-EA), and a 275 gallon tote (XLO27-EA). Using AMSOIL synthetic lubricants does not void a new vehicle or equipment manufacturer warranty, and all AMSOIL lubricants and filters are covered by the AMSOIL Limited Warranty. Match the right grade for the vehicle with the AMSOIL Vehicle Lookup Guide, review viscosity choices across the AMSOIL gasoline lineup in the Car Oil Guide, then order AMSOIL Extended-Life 10W-40 100% Synthetic Motor Oil.
Great oil and filters always have everything I need for all my vehicles super fast shipping I highly recommend.
By Eugenio from Houston tx on July 18, 2026.
Would recommend this to a friend.
Simply the best.
This is only for the people who are planning to use Amsoil for the first time. The people who used it before don’t need to read any reviews.. they know it. This is the best oil by far and it does exactly as the company says. I am using Amsoil for 20 years now on all my cars and never ever had any issues changing my oil every 10 or 25 k miles as recommended.
By Sarkis from Los Angeles on July 14, 2026.
Would recommend this to a friend.
Show me any better
I am using only Amsoil oil for the last 20 years and don’t know (or care) if there is anything better or even close to be equal to it.
10W-40 is an SAE J300 viscosity grade. The 10W rating describes cold-start flow performance at low temperatures, while the 40 describes the high-temperature operating viscosity, which is thicker than a 30-weight oil at full operating temperature. Engines that specify 10W-40 are typically older designs with wider bearing clearances, higher-mileage engines that have started to show oil consumption, and certain heavy-duty gasoline applications where a thicker film at high heat is desirable.
Is Extended-Life 10W-40 a true full synthetic motor oil?
Yes. Extended-Life 10W-40 is a 100 percent synthetic gasoline engine oil. The advanced synthetic base oils are paired with a boosted detergent, dispersant, and acid-neutralizing additive package designed to remain chemically stable through drain intervals of up to 20,000 miles in normal service.
Which industry specifications does the 10W-40 grade meet?
Extended-Life 10W-40 meets API SQ, API SP, API SN Plus, ACEA A3/B3, and ACEA A3/B4. The owner manual should list one of these service categories, or a previous API S category, before the oil is used.
Can Extended-Life 10W-40 be used in older or higher-mileage engines?
Extended-Life 10W-40 is well suited to older engines and higher-mileage gasoline engines that specify a 10W-40 viscosity grade in the owner manual. The thicker 40-weight high-temperature viscosity supports cylinder sealing and oil-film strength in engines with more wear, and the boosted detergent and dispersant chemistry helps clean and protect aging internals. Use the AMSOIL Vehicle Lookup Guide to confirm the correct viscosity for the vehicle.
What is the difference between 10W-40 and 10W-30 in this family?
Both grades carry the same 10W cold-flow rating, so cold cranking behavior is comparable. The 10W-40 is thicker at operating temperature, posting a 100 C kinematic viscosity of 15.4 cSt versus 10.7 cSt for the 10W-30 XLT formula, and a higher HTHS viscosity. Pick 10W-40 when the owner manual calls for it or when sustained heavy-duty loads make a thicker high-temperature film useful.
How long can Extended-Life 10W-40 stay in service?
Extended-Life 10W-40 supports drain intervals of up to 20,000 miles (32,000 km) or one year, whichever comes first, in personal vehicles not operating under severe service. Severe service is limited to 12,000 miles (20,000 km) or one year. AMSOIL Oil Filters are recommended to take full advantage of the extended interval, and other-brand filters should not be run beyond 12,000 miles or one year unless the vehicle manufacturer specifies a longer interval.
Will using AMSOIL Extended-Life void a new vehicle warranty?
No. Using AMSOIL synthetic lubricants or practicing extended drain intervals does not void a new vehicle or equipment manufacturer warranty, and all AMSOIL lubricants and filters are covered by the AMSOIL Limited Warranty.
