Signature Series 5W-50 Synthetic for High Power Ford Mustangs

5w-50 great for high power mustangs!

Signature Series 5W-50 Synthetic Motor Oil is engineered for Mustang Trac-Pack. It combines industry-premier synthetic technology with AMSOIL premium additives in a unique formulation that exceeds the higher performance demands of modern engines.

SKU: AMR Category:
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Offering Specialty Engine Owners a Choice

Back at the 2014 SEMA Show the Mustang took center stage as it celebrated its 50th birthday. In conjunction with this, AMSOIL has added a new viscosity to its Signature Series line specifically formulated for high-horsepower Ford Mustang engines requiring the Ford WSS-M2C931-C performance specification. In Mustangs with the Track-Pack requiring the 5W-50 Synthetic (Ours is 100%)  the oil MUST be tested to meet the Ford WSS-M2C931-C specification. Trust AMSOIL’s 40+ years of true synthetic oils to deliver the performance of these cars.


A New Level of Motor Oil Technology

  • 75% more engine protection against horsepower loss and wear.1
  • 50% more cleaning power vs. AMSOIL OE Motor Oil
  • Protects turbochargers 72% better than required2 by the GM dexos1 Gen 2 specification.
  • 28% more acid-neutralizing power than Mobil 1.3
  • Trusted by professional engine builders
  • Guaranteed protection for up to 25,000 miles or 1 year

Protects Against Engine Wear

5W-50 for mustang AMSOIL Signature Series 5W-50 Synthetic Motor Oil develops a strong fluid film that keeps metal surfaces separated while its robust anti-wear additives further reduce wear in metal-to-metal contact regions for maximum engine life. The Sequence IVA Engine Test, which must be passed to meet the industry-standard API SN specification, simulates extended periods of stop-and-go driving. For 100 hours, the test engine cycles between 50 minutes of idling and 10 minutes of elevated rpm – conditions that encourage engine wear. The camshaft is then measured for wear in 84 locations and an average score is determined. We used Signature Series 0W-20, the lightest viscosity in the line, to further increase the severity of the test. AMSOIL Signature Series Synthetic Motor Oil provided 75 percent more engine protection against horsepower loss and wear1 than required by the industry standard, extending the life of vital components like pistons and cams.

Editors note:
Nothing is held back in the additive blend for the 5W-50 and other Signature Series products. This is why it’s the best in the industry. I’ll quote AMSOIL’s Vice President Dean Alexander, “When selecting additives and base stocks we are the only company who avoids making decisions based on cost. If there is a better product or a trend for something better AMSOIL is known in our industry to be the first to get it to the consumer with our legendary blending experience. That is our business, devoted to being the best, not turning profits for share holders.”
You can also see this technique being used in the Absolute Efficiency Oil Filters.

Forever updated Data Sheet for the Signature Series 5W-50 which will always be updated over the below info.

cam wear prevented with Amsoil Signature Series

After rigorous third-party testing, the cam lobes show little-to-no wear.


Protects Pistons from Low-Speed Pre-Ignition

We armed Signature Series 5W-50 with an advanced detergent system that protects against harmful deposits and low-speed pre-ignition (LSPI). Most new engines feature gasoline direct injection (GDI), often combined with a turbocharger to boost power and improve fuel economy. These new technologies, when combined with a poorly formulated motor oil, promote LSPI and threaten engine operation. LSPI is the spontaneous ignition of the fuel/air mixture prior to spark-triggered ignition. It occurs in today’s advanced engines and is much more destructive than typical pre-ignition.

Original equipment manufacturers (OEMs) like GM* have addressed the issue by designing tests to determine a motor oil’s ability to prevent LSPI. The GM test allows up to five LSPI events to receive a passing score. Signature Series Synthetic Motor Oil provided 100 percent protection against LSPI1 – zero occurrences were recorded.

Pistons are protected in new engines. Here is an LSPI event caused by competitors oil

LSPI is a term you will hear more in the future as manufacturers wait for lubricant companies to catch up..

Protects Turbochargers

Our unique synthetic formulation is inherently stable to resist oxidation and neutralize acids. Signature Series 5W-50 Motor Oil provides outstanding protection against deposits common to high-temperature engine environments. The tremendous heat and stress turbos create can cause some oils to break down and form harmful bearing deposits through a process known as turbo coking. Over time, turbos can suffer reduced performance or fail altogether.

We challenged Signature Series to the GM Turbo Coking Test, which consists of 2000 cycles of extreme heat soaks. An oil must limit the temperature change within the turbocharger to 13 percent or less to pass the test. Signature Series limited the temperature increase to only 3.6 percent, protecting theturbocharger 72 percent better than required2 by the GM dexos1® Gen 2 specification.

totally clean turbocharger parts

Max protection available in a motor oil

Extends Drains: Protection Guaranteed

AMSOIL Signature Series Synthetic 5W-50 Motor Oil provides reserve protection, allowing you to go longer between oil changes if you choose – up to 25,000 miles, 700 hours of operation or one year, whichever comes first*. Our unique synthetic formulation and long-drain additive system are inherently stable to resist oxidation and neutralize acids over longer periods. Signature Series is designed to deliver outstanding engine protection, cleanliness and performance over extended drain intervals – guaranteed. It provides peace of mind so you can fit oil changes into your schedule.

1 Based on independent testing of AMSOIL Signature Series 5w-30 motor oil, in the LSPI engine test as required for the GM dexos 1® Gen 2 specification.
2 Based on independent testing of AMSOIL Signature Series 5W-30 in the GM turbo coking test.
3 vs. AMSOIL OE Motor Oil
4 Based on independent testing of AMSOIL Signature Series 5W-30 in the ASTM D6593 engine test for oil screen plugging as required by the API SN specification.
* 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.

Less horsepower loss measured with AMSOIL products

Preserves Horsepower

The extreme durability of Signature Series 5W-50 Motor Oil ensures your engine runs stronger, for longer. We installed Signature Series 5W-30 Synthetic Motor Oil in a Ford* F-150 with a new 3.5L Ecoboost engine to test its ability to protect turbocharged direct-injection (TDGI) engines from torque and horsepower loss during extended drain intervals up to 25,000 miles. Power sweeps were done at the beginning and end of the test to evaluate horsepower and torque retention. As the graph shows, Signature Series helped maintain engine performance throughout the 100,000 mile test.


Oil consumption is limited

Limits Oil Consumption

Signature Series 5W-50 has a uniform molecular structure that limits evaporation and keeps it where it’s needed most – protecting your engine. Volatility (burn-off) occurs when oil gets hot, causing lighter molecules to burn off or evaporate. This leads to oil thickening, additive imbalance, higher emissions and oil consumption. The NOACK Volatility test is the industry standard for evaluating motor oil high temperature evaporation. It measures the percentage of burn-off after a motor oil is placed under constant airflow at 482ºF for 1 hour. A lower number indicates a better resistance to evaporation. Signature Series falls far below the API limit for volatility, reducing the need for frequent oil top-offs and limiting vehicle emissions.

could pour point of amsoil

Easier Cold-Starts

Signature Series Synthetic 5W-50 Motor Oil does not contain paraffins (wax) and stays fluid in temperatures of -58ºF and lower. Extreme cold causes other motor oils to thicken, starving vital moving parts of lubrication, accelerating wear and even preventing vehicles from starting. Signature Series provides 66 percent better cold-temperature performance for easier starting, better fuel economy, improved oil flow (as seen below) and reduced wear.

viscosity increase and retention


Maintains Protective Viscosity

We formulated Signature Series 5W-50 with superior thermal durability that resists breakdown better than conventional and synthetic motor oils. The Sequence IIIH Test uses the Chrysler 3.6L Pentastar engine to evaluate a motor oil’s ability to resist the damaging effects of heat. The test is conducted with oil temperatures of 304ºF, 100ºF hotter than normal operation, to accelerate oil thickening and deposits. Despite the extreme conditions, Signature Series kept pistons clean and held thickening to only 6 percent, a minimal amount compared to the proposed specification limit of 150 percent.1 This stay-in-grade performance helps maintain maximum power and fuel economy while also ensuring advanced technologies like variable valve timing (VVT) operate as designed throughout the entire drain interval.

1 Based on proposed ILSAC GF-5 Plus specification.
* 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.

Peter Markham, Regional Sales Manager

AMSOIL makes you smile because you love products with full disclosure!



AMSOIL Signature Series Synthetic Motor Oil is excellent for use in all types of gasoline-fueled vehicles. It is recommended for all domestic and foreign vehicles requiring any of the listed performance specifications:

5W-50 (AMR): API SP, SN PLUS, SN…; Ford WSS-M2C931-C (Mustang); GM dexos R

“Just by switching I first noticed the engine seem to run as smooth as glass. Suddenly I realized why AMSOIL products stand alone in quality. You won’t realize the coarseness or vibrations within the motor until they are gone. AMSOIL 5W-50 Synthetic Motor Oil was worth every sent!

5W-50 Mustang Oil Service Life

Normal Service – Up to 25,000 miles, 700 hours of operation or one year, whichever comes first, in personal vehicles not operating under severe service.
Severe Service – Up to 15,000 miles, 700 hours of operation or one year, whichever comes first. Severe service conditions include commercial or fleet vehicles; excessive idling; or frequent
towing, hauling, plowing or driving in dusty conditions.

  • Modified engines (non-stock), racing vehicles and vehicles
    using alternative fuels (E85, CNG, propane, etc.) are excluded
    from extended drain interval recommendations.
  • Change at the vehicle manufacturer’s recommended drain
    interval outside U.S. and Canada.
  • AMSOIL Ea® Full-Flow Oil Filters are designed for extended drain
    intervals. Do not exceed 12,000 miles or one year with other
    brand filters unless longer intervals are recommended by the
    vehicle manufacturer. Always change filter when changing oil.
  • Check oil regularly to maintain proper fill levels.

AMSOIL Ea Full-Flow Oil Filters stop smaller particles, flow more oil and last longer than regular filters. For best performance, use AMSOIL Ea Full-Flow Oil Filters.


5W-50 (AMR): API SP, SN PLUS, SN…; Ford WSS-M2C931-C (Mustang); GM dexos R

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

Aftermarket oil additives are not recommended for use with AMSOIL synthetic motor oils.

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AMSOIL products are backed by a Limited Liability Warranty. For complete information visit

Product Reviews – AMSOIL Signature Series

star rating

I Love amsoil
By  GARY,  a  Verified Buyer  from  Old orchard beach Maine   on  November 12, 2022
I changed oil brands from Mobile 1 to amsoil. I could feel the change in power and fuel mileage almost immediately. Love it..
By  COYOTE,  a  Verified Buyer  from  MONTANA  on  October 26, 2022
Smooth running engine
By  JAMES,  a  Verified Buyer  from  Cincinnati Ohio   on  January 24, 2023
I can tell my engine likes this oil, runs very smooth and my gas mileage increased.
star rating

A cut above the rest
By  ROBERT,  a  Verified Buyer  from  East Hartford, Connecticut  on  March 05, 2023
I drive my car hard and sometimes tow. I always look for the highest quality oils to use. I like to do my own maintenance on all my vehicles. I like to know exactly what oil is being used. Amsoil is my choice for my car, truck and motorcycle. The signature series is the top of the line and that’s what I look for.
AMSOIL 100% synthetic motor oil
By  Jr,  a  Verified Buyer  from  Reseda, California  on  January 26, 2023
AMSOIL 100% synthetic motor oil is one of the best engine oils on the market for any vehicle. Just like how clean blood is vital to the success of how our body operates, the types of motor oil you choose can also affect the success of your motor. After 6K on my AMSOIL 100% synthetic oil, I had an oil analyst test done on the oil. It passed with flying colors! The lab indicated, for my style of driving, it was suggested I could drive 10K-12K between oil changes with the current oil I’m using. I would never go that long between oil changes; however, I usually change my oil every 7K or every 6 months. It’s reassuring to say the least to change my motor oil knowing that it is still capable of protecting my motor many miles beyond.
I use Amsoil in everything I ride and drive.
By  WillyDaC50,  a  Verified Buyer  from  Moreno Valley California  on  October 30, 2022
When I switched to Amsoil nearly a decade ago, I did it because trying to navigate the different lubricants available was getting crazy. Everything I own has Amsoil in it, my Bonneville bike was my test bed. So, when I purchased a Coyote engine F150 I came home and dumped whatever was in it and did a change using Amsoil. My oil is always my first and most consistent thing about my vehicles. Not having to concern myself about lubrication takes a load off my mind.
Great Quality
By  CHRIS,  a  Verified Buyer  from  Birmingham Alabama   on  December 11, 2021
Oil has performed very well and has not burned off in highly modified 700hp M5. I have run Redline and Moly in this car and the analysis of the oil after the first change has been superior to both.


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