Signature Series 0W-40 Synthetic Motor Oil

AMSOIL Signature Series Synthetic 0W-40 Motor Oil 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.

This is the best choice out there for the Nissan GT-R Twin Turbo Engine. Designed for vehicles under warranty including the 3.8 L VR38DETT twin-turbo V6. Unlike the OEM recommendation, this is a REAL synthetic that will not coke up the turbo charger lines.

Also specifically designed to meet Chrysler’s Supercharged 6.2 Hellcat

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0W-40 versus 5W-40 Hot Topic in Forums

Oil experts can tell a customer this is the right oil to use all day but the hear in forums that something thicker will offer better protection. And that the service center is “now” saying to use another weight, etc..   Well finally I found one post that was so clear it was as if I was a member in that forum. I have posted it at the bottom of this page. But all you need to know is the number to the right which in this case is the 40, is the actual viscosity. The “0W” or 5W or 10W,  is not an actual reference to any specific flow quality but to a sliding scale based on the number on the right.  So more simply, a 0W-40 and a 5W-40 are both the exact same at operating temperature. Once that oil reaches the normal temp of 100C or 212F, it is within a certain viscosity range measured in Centistokes or how it reacts under gravity.
Now that said, the W indicator is more of a classification explaining the cold cranking loss in the form of Brookfield Viscosity. The test is sort of a blender like machine measuring resistance. Maximums are set but between brands and base stocks the results may be at the minimum limit or in the case of a true synthetic of quality – way below the scale meaning the oil is there when it’s expected.  Now – it may seem thinner at room temperature but no matter how it appears in the bottle, it gets a LOT thinner as it warms up. So to say a 5W-40 is going to provide more protection than a 0W-40 is total hogwash.. My way of explaining this is the lower the “w” or start-up classification, the more advanced the technology. That’s why wise road racers prefer 0W-30 over 5W-30 or 10W-30 because it’s just an indicator of a better oil plain and simple.

0W-40 Sells and the Customers in Omaha know a Good Product

In the Omaha store we are now selling as much of this as we sell the 10W-30 these days.. SO we WILL keep plenty in stock. It’s hard to find a good version of any 0W-40 not to mention a “Real” synthetic labeled as 100% so once again your Omaha AMSOIL dealer has it in stock. Even the local Dodge/Chrysler dealers are stopping by to pick it up per customer requests.


Protects Against Engine Wear

signature series 0w-40AMSOIL Signature Series 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.

Download Product Data Bulletin

SEQUENCE IVA ENGINE TEST Lower number = less wear
Lower number = less wear
Lack of Cam wear

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

1Based on independent testing of AMSOIL Signature Series 0W-20, in ASTM D6891 as required by the API SN specification.

Protects Pistons from Low-Speed Pre-Ignition

We armed Signature Series 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. A properly formulated motor oil is critical for protecting your engine.

Original equipment manufacturers (OEMs) like GM* have addressed the issue by designing tests to determine a motor oil’s ability to prevent LSPI. Signature Series Synthetic Motor Oil achieved 100 percent protection against LSPI1 in the engine test required by the GM dexos1 Gen 2 specification – zero occurrences were recorded throughout five consecutive tests.

Protects Turbochargers

Our unique synthetic formulation is inherently stable to resist oxidation and neutralize acids. Signature Series 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 the turbocharger 72 percent better than required2 by the GM dexos1® Gen 2 specification.

Protects Turbochargers

Signature Series Badge

Extends Drains: Protection Guaranteed

AMSOIL Signature Series Synthetic Motor Oil provides reserve protection, allowing you to go longer between oil changes if you choose – up to 25,000 miles (40,200 km), 700 hours of operation or one year, whichever comes first (see back page for details). 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.

Preserves Horsepower

The extreme durability of Signature Series Motor Oil helps your engine run 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 (40,200 km). 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 (160,934 km) test.

Horsepower increased thanks to AMSOIL Signature series


Limits Oil Consumption

Signature Series 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 (250ºC) 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.

less oil consumption

Easier Cold-Starts

Signature Series Synthetic Motor Oil does not contain paraffins (wax) and stays fluid in temperatures of -58ºF (-50ºC) 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.

Cold flow and srarts

Keeps Pistons Cleaner

We formulated Signature Series with superior thermal durability that resists breakdown and keeps pistons clean. The Sequence IIIH Test uses the Chrysler* 3.6L Pentastar* engine to evaluate a motor oil’s ability to resist heat and keep pistons clean. The test is conducted with oil temperatures of 304ºF (151ºC), much hotter than normal operation, to accelerate oil thickening and deposits. A single-length 90-hour test didn’t even challenge Signature Series. Its viscosity was like that of new oil, and the pistons were still nearly spotless. To really test the oil, we told the lab to reassemble the engine and run the test again using the same oil. Even after doubling the length of the industry-standard test, the oil limited oil thickening to well under the allowable threshold while delivering 40 percent cleaner pistons than required by the standard.1

Viscosity Retention

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.

More information can be found about the Signature Series 5W-20 on this printable DATA SHEET covering service life and more.

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.




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

0W-40 (AZF): API SP, SN PLUS, SN…; Chrysler MS-12633, MS-10725, MS-10850; Nissan GT-R


AMSOIL Signature Series Synthetic Motor Oil is compatible with other conventional and synthetic motor oils. Mixing other oils with AMSOIL motor 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.


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


Normal Service – Up to 25,000 miles (40,200 km), 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 (24,140 km), 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 Oil Filters are designed for extended drain intervals. Do not exceed 12,000 miles (19,312 km) 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 Oil Filters stop smaller particles, flow more oil and last longer than regular filters. For best performance, use AMSOIL Oil Filters.


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 or upon request at 715-392-7101. Keep Out of Reach of Children. Recycle used oil and bottle.

Don’t pollute. Return used oil to collection centers.

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.

Confidence in 0W Multi-Weight Oils

This reply to the confusion of 0W-40 versus 5W-40’s or 10W-40 was in a Chrysler SRT forum. The author did a great job helping the debaters understand their worry is strictly superficial. I post this here on a product page rather than as a blog entry knowing someone searching for the same advice on the subject would find it in searches.

He starts as a reply to another member who was warned by a service tech that the recommended 0W-40 would cause harm and to use 5W-40 now

The guys at that shop are idiots. They clearly don’t understand how the viscosity of an engine oil is rated.

Although the 5W-40 oil may pour marginally slower out of the bottle (than the 0W-40), that does not mean that it is a thicker oil at operating temperature. (This is probably about as far as their thinking goes).
The operating temperature viscosity is rated at 100C (210F) and a 40 weight oil can be anywhere from 12.5 – 16.29 centistokes (cST). The point being is that the rating is a range – it is not one specific thickness (or viscosity).

Without knowing what brand/flavour of oil you are running & what the garage wants to use it is impossible to say which is “thicker.” Difference in base stocks, additives, etc. will alter the characteristics of an oil. I won’t even begin to attempt to touch the subject of mineral (group II) vs. synthetic (whether it be group III, IV, V).

Remember… the upper number is the more important number. Whether you run 0W-40, 5W-40, 10W-40, 15W-40 – at operating temperature they will all be similar in viscosity. This doesn’t mean that you can/should run any of the oils in your engine – if the manufacture recommended 5W-40… then in your location, a 15W-40 could be too thick in freezing weather and cause lubrication starvation issues at start-up.

I agree with Kevin – the manufacturer would have had a sliding scale for viscosity based on mileage if it was warranted.

No oil (doesn’t matter if it is $2 bargain store or $20 exotic oil) will fix a worn out engine (at 65K yours should not be anywhere near being worn out). And stay away from additives – they are a bandaid at best and usually they only accomplish in making your wallet thinner.

Find yourself a new shop.

Personally, I change my own oil (I know not everyone can or wants to) or I use an intelligent independent mechanic if the situation requires.
Quick lubes are on my do not visit list.

Customer Comments:

Can’t run without the best.
By Royce 12/17/2016

from undisclosed

Excellent product, improves gas mileage and reduces engine wear.

Highly recomended
By Greg 12/28/2016

from undisclosed

Great oil been using in my toyota tacoma I change the filter at 10k (EA) and complete drain at 20k. Truck doesnt smoke and runs great with 225k miles

Signature series is your best investment.
By Denis 12/27/2016

from undisclosed

Best oil on the market !
Runs cooler and lasts longer. I’ve run both coasts from Colorado, 3 different Harley’s. Run amsoil in all my vehicles