Signature Series 5W-50 Synthetic Motor Oil

Signature Series 5W-50 Synthetic Motor Oil

About the Signature Series Line

AMSOIL Signature Series Synthetic Motor Oil (5W-50) is engineered to outperform conventional and synthetic motor oils. It combines industry-premier synthetic technology with AMSOIL premium additives in a unique formulation that exceeds the higher performance demands of modern engines. Signature Series delivers the performance and value upon which the AMSOIL reputation is built. The culmination of more than 40 years of expertise, its exclusive formulation raises the bar for motor oil performance.


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Signature Series 5W-50

AMSOIL has expanded the Signature Series line to include a robust 5W-50 synthetic motor oil formulated specifically for high-horsepower Track-Pack Ford Mustang engines. Signature Series 5W-50 Synthetic Motor Oil (AMR) provides top-of-the-mark protection and performance that customers expect from Signature Series, and it is excellent for all Mustang engines calling for a 5W-50 viscosity. We’re you Omaha oil source for everything Mustang!! Delighted to help you.

AMSOIL, the leader in automotive synthetic lubrication, produced the worlds first API-qualified synthetic motor oil in 1972. Trust the extensive experience of AMSOIL, the First in Synthetics®, to do the best job protecting your engine.


Protects Your Engine

AMSOIL Signature Series Synthetic Motor Oil provides outstanding anti-wear protection. It 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. In the industry-standard Sequence IIIG Engine Test, AMSOIL Signature Series Synthetic Motor Oil delivered 75 percent more engine protection against horsepower loss and wear than required by a leading industry standard.** For details, see the Double-Length Sequence IIIG Engine Test Technical Study (G3320).

Download and Printable Product Data Bulletin

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Maximizes Fuel Economy

Signature Series Synthetic Motor Oil is designed to maximize energy efficiency for optimum fuel economy. Unlike conventional oils, its uniform molecular structure helps it flow more freely and reduce friction between metal surfaces. Anti-friction additives are included to further improve energy efficiency.

Extends Drain Intervals

AMSOIL Signature Series Synthetic Motor Oil can extend drain intervals far beyond those recommended for conventional oils. Its 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. It reduces vehicle maintenance and waste oil.

Keeps Pistons Clean

Excess piston deposits can lead to pre-ignition and engine knocking, which results in lost power, reduced fuel economy and, in severe cases, engine damage. Signature Series’ premium additives and naturally high resistance to extreme heat help keep pistons clean for maximum engine performance. Signature Series prevents piston deposits 93 percent better than required to meet the latest API standard.**

piston after double-length sequence IIIG engine test


Excels in Extreme Temperatures

Signature Series 5W-50 resists thermal (heat) breakdown better than conventional and synthetic motor oils. It is heavily fortified with detergent and dispersant additives to help prevent sludge deposits and keep engines clean. Unlike conventional oils, Signature Series contains no wax, staying fluid in sub-zero temperatures for easier starting, improved oil flow and reduced wear.

Reduces Oil Consumption and Emissions

Volatility (burn-off) occurs when oil gets hot, causing high oil consumption and emissions. Signature Series resists volatility better than other oils, helping reduce oil consumption and emissions.


Match Your VehicleProduct Guides

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

5W-50 (AMR): API SN, SM…; Ford WSS-M2C931-C (Mustang)

*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 AMSOIL-engineered for use in the applications shown.


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.


  • 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: Primarily short trips (less than 10 miles [16 km]); turbo/supercharged engines; commercial or fleet vehicles; excessive idling; first-time use of AMSOIL motor oil in a vehicle with more than 100,000 miles; frequent towing, hauling, plowing or driving in dusty conditions.

  • Modified engines (non-stock) and those using E85 fuel are excluded from extended drain 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 change intervals. With other brands, do not exceed six months or 10,000 miles unless longer intervals are recommended by the vehicle manufacturer.
  • Check oil regularly to maintain proper fill levels.

AMSOIL Ea® Full-Flow Oil Filters are designed for extended change intervals. They stop smaller particles, flow more oil and last longer than regular filters. For best performance, use AMSOIL Ea Full-Flow Oil Filters.

On the Ford Mustang’s engine has a specific calibration for the Ti-VCT timing to work with the 5w-50 oil.  This is the FORD recommendation for the Boss 302 or Track Pack GT. I’ve read about people using other viscosities because the Motorcraft version was sheering out. But that is why you use AMSOIL because it’s guaranteed not to sheer out within it’s guaranteed intervals listed above. AMSOIL offers quality and protection for your Mustang investment AND allows you to get full efficiency from the motor in all driving conditions. Track or commuting.

Buy in the Omaha store at 84th & G or use this Online link to the Amsoil sale page if you are outside of the area. We keep plenty in stock so please tell your Mustang friends and club members about us.

AMSOIL Signature Series 5W-50 100% Synthetic Motor Oil | AMR – AMSOIL


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

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Customer Comments:


Wonderful Again (2nd update)

By  CAMERON,  a  Verified Buyer  from  Utah  on  January 18, 2024
I love this oil. I’ve been using it in my 2010 370z, it’s a daily and a track car. I was not expecting to feel such a difference when switching from Mobil 1 to this signature series. And my over all oil temperature stays below 200° before it would sit right around 240°

Big Fan of Amzoil

By  BLAIR,  a  Verified Buyer  from  Rhode Island  on  January 15, 2024
Big Fan of Amzoil because of the extended oil change. Back in the 1990’s I was working in the racing industry (SCCA) on the weekends. What that meant was an average of 30,000 to 40,000 miles of driving and working 80 to 100 hours a week during the racing season. I never had an engine problem was running Amzoil. A mechanic that worked in the industry could not believe how nice the engine ran for the mileage on it and how good it looked inside. He started using it right away too.

Amsoil Oil

By  JASON,  a  Verified Buyer  from  San Antonio  on  January 10, 2024
Only use this oil in my 23 Shelby f150 truck. Best oil on the market for performance and reliability!

Great product

By  GREGORY,  a  Verified Buyer  from  Newbern, TN  on  January 07, 2024
This is a great product that actually works. I read about people who write that this oil is too expensive. It’s actually cheaper in the long run to use high quality oil than to use questionable quality oil that just barely meets the requirements. I use AMSOIL on all all three of my vehicles and my riding mower. One of my vehicles has over 304,000 miles, my next vehicle has 280,000 miles, and my third vehicle has 208,000 miles on it.
By  CAMERON,  a  Verified Buyer  from  Utah  on  November 27, 2023
Lots of people believe that most of the additives and selling points in motor oil is just snake oil. And I would say there is definitely some truth to that, I don’t know what is real or not but I do know I can feel quite a significant difference when I switched to amsoil. My 370z runs super clean and very smooth. It was smooth before but I didn’t realize how smooth it could be until I switched. Your car will thank you

What the Boss has for Breakfast
By Grabber Blue Greggor 8/29/2016

My ’13 Boss 302 takes an odd oil grade….5W-50…and only a few brands offer it…and when they do it’s usually formulated for older Muscle cars….so it’s loaded with Zinc additives…very detrimental to modern catalytic converters….plugs them up.
AMZOIL created their Signature 5W-50 specifically to address Fords running the HO versions of the newer 5.0 V-8s !
The Boss loves it for Breakfast and never Burps. Thanks AMZOIL!! Super Product!