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.

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 Sioux Falls know a Good Product

In the Sioux Falls 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 Sioux Falls AMSOIL dealer has it in stock. Even the local Dodge/Chrysler dealers are stopping by to pick it up per customer requests.

Devoted to Quality and the Leading Position in the Industry

Signature Series 0W-40 Synthetic Motor OilAMSOIL, the leader in automotive synthetic lubrication, produced the world?s 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 0W-40 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).

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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.

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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.**

Excels in Extreme Temperatures

Signature Series 0W-40 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.


AMSOIL Signature Series Synthetic 0W-40 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:

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

Supersedes specific European spec oils as this is tested beyond the requirements above.

*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.


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

Buy in the Sioux Falls AMSOIL store at 4610 W. 12th St. or use this Online link to the Amsoil sale page if you are outside of the area.

Keep Out of Reach of Children. Don’t pollute. Return used oil to collection centers.

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