AMSOIL Signature Series 100% Synthetic Motor Oil is engineered for enthusiasts seeking maximum protection and performance. It’s precision-formulated with cutting-edge technology and a longstanding devotion to making the world’s best motor oil. The result: engine protection that blows the doors off the highest industry standards.
How good is it? Signature Series is the best motor oil we have ever made. Advanced engine technology and rigorous demands placed on modern vehicles can challenge motor oil, eventually leading to decreased engine performance and life. Signature Series delivers the ultimate protection against extremes like high-performance driving, off-roading, towing and extended idling. Its boosted protection also lets you drive further between oil changes.
Some may claim that Signature Series Motor Oil is overbuilt. Perfect. It’s not for everyone. It’s for those who want the absolute best engine protection. Is it the right motor oil for you? Learn how to compare synthetic motor oils and judge for yourself.
Do you want to prevent horsepower loss and wear?
Dirty or worn components work poorly and don’t last. They cause system failures in engines that dramatically increase maintenance costs and reduce vehicle life. Clean and protected engine components, on the other hand, require less maintenance, produce more horsepower, are more fuel efficient and help increase engine life.
Signature Series 100% Synthetic Motor Oil develops a strong fluid film that keeps metal surfaces separated. Its advanced anti-wear additives further reduce wear in metal-to-metal contact regions for maximum engine life.
How do we know? We put Signature Series 5W-30 in a 2025 Ford F-150 Raptor and ran it for 125,000 miles, changing the oil at 25,000-mile intervals. Horsepower and torque were measured with power sweeps before and after the test.
Signature Series maintained horsepower and torque throughout the entire 125,000-mile test, even under the elevated stresses of a high-output engine.1 Read the full story in Hold On to Your Power.
Do you drive in hot temperatures?
Engine sludge is the result of a series of chemical reactions that cause oil to degrade. These reactions are driven by exposure to oxygen and elevated temperatures. The higher the temperature, the more rapid the rate of degradation. In fact, every 18°F (10°C) increase in operating temperature doubles the rate of oxidation.
The byproducts of this reaction form highly reactive compounds that further degrade the lubricant. These byproducts react with other contaminants, forming organic acids and high-molecular-weight polymeric products. These products further react, forming the insoluble product known as sludge. What begins as a thin film of lacquer or varnish builds up on hot or cold metal surfaces and bakes into an expensive mess.
Signature Series is engineered to resist that breakdown. During the 125,000-mile Raptor study, the engine experienced 0% oil screen plugging.2 See No Sludge. Just Protection..
We engineer 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 90-hour test is conducted with oil temperatures of 304°F (151°C), much hotter than normal operation, to accelerate oil thickening and deposits.
In the Sequence IIIH test, Signature Series delivered 72% more protection against piston deposits than required by industry standards.3 Even when the test length was doubled, it provided 31% better protection than required.4 Learn more in Clean and Powerful Pistons: Signature Series and the Sequence IIIH Test.
Heat also boils off an oil’s lighter molecules. This volatility leads to oil consumption and deposits. Signature Series delivers 2X better protection against volatility.5 See Quantifying Performance.
Do you have long commutes?
Do you rack up the miles on your vehicle? Signature Series 100% 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) or one year, whichever comes first. Our proprietary 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. See AMSOIL oil change intervals for severe-service guidelines.
Signature Series keeps engines cleaner, longer. It is fortified with a heavy treatment of detergent additives to help keep critical components clean throughout extended drain intervals. For the cost side of the equation, see A Data-Driven Guide to Slashing Maintenance Costs with AMSOIL.
Does your vehicle have a turbocharger?
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.
Turbocharged engines run hotter and harder, so heat resistance and deposit control matter even more. Signature Series is formulated to resist thermal breakdown and fight deposit formation. In the 125,000-mile study, it maintained horsepower and torque in the high-output engine of a Ford F-150 Raptor.1 Turbocharged direct-injection engines also face low-speed pre-ignition, covered below.
Do you want better startup protection?
Most engine wear occurs at startup. That’s primarily because oils thicken as the temperature drops. Cold oil doesn’t flow as fast and, in some cases, may not be able to flow through tiny oil passages at all. When that happens, engine components are forced to operate without lubrication until the engine warms up the oil enough for it to flow, greatly accelerating wear. For those reasons, cold-flow capability is a critical measure of motor oil performance.
Signature Series is formulated to flow in extreme cold. Pour point, the lowest temperature at which an oil still flows, ranges from -48°C (-54°F) to -54°C (-65°F) across the Signature Series lineup, according to its data sheet. More in Superior Cold-Start Engine Protection.
Do you want to guard against LSPI?
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.
Signature Series is armed with an advanced detergent system that protects against harmful deposits and low speed pre-ignition (LSPI). Engines equipped with gasoline direct injection (GDI) and a turbocharger provide boosted power and fuel economy. But when these technologies are combined with poorly formulated motor oil, LSPI can become a real threat for the engine.
Vehicle manufacturers like GM* have addressed the issue by designing tests to determine a motor oil’s ability to prevent LSPI. Even after 25,000 miles of use, AMSOIL Signature Series 100% Synthetic Motor Oil delivers 4X more piston protection against LSPI than the industry standard requires.6 See Protecting Against LSPI – Even During Extended Drain Intervals.
Do you trust professional performance engineers?
AMSOIL and Lingenfelter Performance Engineering (LPE) are strategic partners with a mission to push the bounds of vehicle performance. AMSOIL products are the “Official Lubricants of LPE.”
“The choice for us was performance based,” said Mark Rapson, COO/VP of Operations for Lingenfelter Performance Engineering. “We are continuously pushing the performance envelope of today’s late-model platforms. 700+ hp, high-rpm, naturally aspirated engines and 1,000+ hp supercharged and turbocharged street cars are now very common. The technology that makes this possible – computerization, DI, hotter and leaner combustion cycles – all bring special demands to engine components, including motor oil.
“During our R&D work, we began to experiment with and evaluate top oil brands to understand performance differences in given applications,” continued Rapson. “We were surprised at the differing results and found that AMSOIL gave the best performance in our application. This led us to contact AMSOIL.”
1Based on comparative start- and end-of-test horsepower and torque measurements in a 125,000-mile accumulation study with AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil in a 2025 Ford* F-150 Raptor* equipped with a 3.5L high-output engine. 2As demonstrated in a 125,000-mile accumulation study using AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil in a 2025 Ford* F-150 Raptor* equipped with a 3.5L high-output engine which had 0% oil-screen plugging. 3Based on AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil results in the Sequence IIIH test. 4Based on AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil results in a double-length Sequence IIIH test. 5Based on AMSOIL Signature Series 0W-20 100% Synthetic Motor Oil compared to the API SQ limit using the ASTM D5800 NOACK volatility test. 6Based on AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil in the Sequence IX aged-oil LSPI test after 25,000-mile service interval.
The Signature Series guide
Each result above has its own deep dive:
- Raising the Bar for Performance – Again
- New Formula, Same Promise: Maximum Engine Life and Performance
- Hold On to Your Power
- Clean and Powerful Pistons: Signature Series and the Sequence IIIH Test
- Quantifying Performance: Signature Series Motor Oil and the NOACK Volatility Test
- Protecting Against LSPI – Even During Extended Drain Intervals
- No Sludge. Just Protection.
- How Engine Sludge Forms. And How to Prevent It.
- A Data-Driven Guide to Slashing Maintenance Costs with AMSOIL
- AMSOIL Oil Change Interval
- Unbreakable Timing Chain Protection
- Superior Cold-Start Engine Protection
- Your Ultimate Oil Change
This article is part of our Car and Truck Motor Oil guide. See every article in the guide.
Recommended AMSOIL products
Start with AMSOIL synthetic motor oil and find the exact AMSOIL products for all your vehicles with the AMSOIL Product Guide.
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Brad Nelson is an AMSOIL Technical Writer II who develops content about lubricant technology, product performance and vehicle maintenance. He works with engineers and product specialists to translate testing, application requirements and approved performance claims into clear customer guidance. Nelson’s work includes AMSOIL Blog articles, AMSOIL Magazine features and technical explanations concerning motor oils, gear lubricants, vehicle systems and maintenance practices.
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