XL 10W-40 Synthetic Motor Oil

Boosted Protection For Extended Life

Note: As we have very few vehicles that us a 10W-40 these days and those which do require zinc additives or are specific for motorcycles, ATV and other specific uses, I don’t carry this one in the store. The reason is because I have several other 10W-40 and 5W-40’s that AMSOIL makes which are more specific including the original AMSOIL product the AMO 10W-40 which is 100% synthetic and can be used in almost anything.. Motorcycles included!

If you need it just call and I’ll order it in to the Omaha store. Call me at 605-274-2580.

Resists Oil Breakdown

AMSOIL Extended-Life 10W-40 100% Synthetic Motor OilXL Synthetic Motor Oil maintains its fluidity (viscosity) under the most extreme conditions. Some oils break down and significantly increase in viscosity after extended periods of high-temperature operation. These changes can cause excessive oil consumption, engine deposits, accelerated wear and difficult cold-starts. The GM Oxidation and Deposit (GMOD) Test consists of a 5.7L V8 engine running at 293ºF (100º hotter than normal) for 100 hours. These severe operating conditions test an oils ability to control viscosity increase, deposits and oil consumption. The testing revealed that AMSOIL XL Synthetic Motor Oil provides 64 percent more protection against oil breakdown1 than required by the GM dexos1® Gen 2 specification, ensuring protection in extreme temperatures.

Download Product Data Bulletin

Buy & Check PriceAnd Container Size

Buy in the Omaha store at 84th & G or use this Online link to the XL 10W-40 sale page if you are outside of the area.

Protects Pistons from Low-Speed Pre-Ignition

XL Synthetic Motor Oil features unique chemistry proven to protect your engine against the harmful effects of low-speed pre-ignition (LSPI). LSPI is the spontaneous ignition of the fuel/air mixture prior to spark-triggered ignition. Most new engines feature gasoline direct-inject (GDI), often coupled with a turbocharger. These technologies heighten the possibility of LSPI events, which can destroy pistons and connecting rods. A properly formulated motor oil is critical for protecting your engine against LSPI.

Original equipment manufacturers (OEMs) like GM have addressed the issue by designing tests to determine a motor oil’s ability to prevent LSPI. XL Synthetic Motor Oil achieved 100 percent protection against LSPI2 – zero occurrences were recorded throughout five consecutive tests.

Keeps Engines Clean

AMSOIL XL Synthetic Motor Oil is fortified with detergent and dispersant additives. Its boosted additive package effectively raises the total base number (TBN) to neutralize acids and resist sludge, corrosion and carbon deposits. XL provides 25 percent more cleaning power3 to help keep your engine running smoother, longer.

Reduces Maintenance

Motorists, business owners and fleet managers benefit from the boosted engine protection of AMSOIL XL Synthetic Motor Oil. Frequent oil changes are expensive, time-consuming and inconvenient. The extra protection built into XL can provide extended drain intervals up to 12,000 miles or one year4, if you choose, allowing you to change oil on your schedule, reduce maintenance, save money and reduce waste oil.

Maximizes Fuel Economy & Maintains Low Emissions

XL Synthetic Motor Oil is licenced by the American Petroleum Institute (API) to meet and exceed the requirements commonly found in owner’s manuals. It excels in fuel-economy testing, earning the additional “Resource Conserving” designation5 from the API. XL is also friendly toward modern emissions control systems, promoting proper operation of catalytic converters for optimum service life and low exhaust emissions.

1Based on independent testing of AMSOIL XL 5W-30 motor oil in the GMOD engine test required for the GM dexos1 Gen2 specification.

2Based on zero LSPI events in five consecutive tests of AMSOIL XL 5W-30 Motor Oil in the LSPI engine test required by the GM dexos1 Gen 2 specification.

3vs. AMSOIL OE Motor Oil

4See reverse side for details.

5Applicable to XL 0W-20, 5W-20, 5W-30 and 10W-30 motor oil.

All trademarked names are the property of their respective owners and may be registered marks in some countries. No affiliation or endorsement claim, express or implied, is made by their use.


Use AMSOIL XL Synthetic Motor Oil in applications that require any of the following specifications:

10W-40 (XLO)

  • API SN, SM…; ACEA A3/B3, A3/B4


AMSOIL XL Synthetic Motor Oil is compatible with conventional and other synthetic motor oils. Mixing other oils with AMSOIL motor oils, however, will shorten the oil life expectancy and reduce the performance benefits. AMSOIL does not support extended drain intervals where oils have been mixed.

Aftermarket oil additives are not recommended for use with AMSOIL XL Synthetic Motor Oil.


For immediate answers to your technical questions call (715) 399-TECH (8324) between 8 a.m. and 5 p.m. Central time or email tech@amsoil.com.


In gasoline-fueled vehicles, AMSOIL XL Synthetic Motor Oil is recommended for up to 12,000 miles/one year oil change intervals, or longer when recommended in owner’s manuals or indicated by electronic oil life monitoring systems. Change the
oil filter at every oil change regardless of filter brand.


Using AMSOIL synthetic lubricants or practicing extended drain intervals does not void your new vehicle or equipment manufacturer’s warranty. All AMSOIL products are backed by a Limited Liability Warranty. For complete information visit AMSOIL Warranty Information/.


This product is not expected to cause health concerns when used for the intended application and according to the recommendations in the Safety Data Sheet (SDS). An SDS is available via the Internet at www.amsoil.com or upon request at 715-392-7101. Keep Out of Reach of Children. Recycle used oil and bottle.

*All trademarked names and images are the property of their respective owners and may be registered marks in some countries. No affiliation or endorsement claim, express or implied, is made by their use. All products advertised here are developed by AMSOIL for use in the applications shown.


Customer Comments:

No need for Signature Series oil…XL Works Great!
By Mark 12/24/2016

from undisclosed

I find that the XL works great, and is not as expensive as the Signature Series. I change the oil every 6 months or 5-7000k miles regardless, so I see the XL as excellent for those of us who do regular fluid maintenance.


Excellent product for the money.
By William 12/26/2016

from undisclosed

For years, I used mobil1. When the time came, I switched to Mobil 1 high mileage. About 2 years ago I started to get a subtle knock coming from the bottom end of the motor. It also started to use oil between oil changes. When I switched to Amsoil, not only did the knock go away immediately, my now 170,000 mile engine consumes no oil between oil changes.


Still using Amsoil
By Joe 1/1/2017

from undisclosed

Many years ago I had an 87 ford f150 with lifter noise at 100k miles. I ran across an Amsoil dist. at that time, I changed to Amsoil, noise went away and I put another 150k miles on the truck and the engine was still quiet when I sold it. All I ever did to it was a new timing chain. Been using Amsoil ever since in every vehicle.