Engineered for enthusiasts seeking maximum protection and performance. Precision-formulated with cutting-edge technology and a longstanding devotion to making the worlds best motor oil. The result: engine protection that blows the doors off the highest industry standards.

Fights Engine Wear

* 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.
* Develops a strong fluid film that keeps metal surfaces separated.
* Robust anti-wear additives further reduce wear in metal-to-metal contact regions for maximum engine life.1Based on independent testing of AMSOIL Signature Series 0W-20, in ASTM D6891 as required by the API SN specification.
Signature Series Improves Startup Protection
AMSOIL provides better cold cranking viscosity, helping improve wear protection for engine components at startup.PP
ASTM D5293 cold Crank (Lower = Better)

AMSOIL Signature Series(5W-30)
Royal Purple High Performance (5W-30)
Lucas (5W-30)
Driven LS30 (5W-30)
Red Line High Performance (5W-30)
Royal Purple HPS (5W-30)
Cranking Viscosity ( s)
3800
4500
5000
5750
6100
6100
PPBased on independent third-party testing in the industry-standard ASTM D5293 Cold Crank Simulator test as required by SAE J300. *Trademark 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.
Signature Series Fights Wear
75% more engine protection against horsepower loss and wear.A
Sequence IVA Engine Test – Lower Number = Less Wear

Industry Standard
AMSOIL Signature Series 0W-20 Synthetic Motor Oil
Average Cam Wear
90
20.28
ABased on independent testing of AMSOIL Signature Series 0W-20, in ASTM D6891 as required by the API SN specification.
Signature Series Delivers Powerful Protection
AMSOIL delivers powerful protection. How good is it An independent lab compared AMSOIL synthetic motor oil head-to-head against a leading competitor in a 100,000-mile test.P AMSOIL provided far superior wear protection and kept bearings looking like new.
PTesting conducted in an independent lab using AMSOIL Signature Series 5W-30 Synthetic Motor Oil and a leading synthetic-blend 5W-30 motor oil in Ford F-150 trucks with 3.5L twin-turbo engines.
Signature Series Protects Against LSPI
AMSOIL Synthetic Motor Oils achieved 100% protection against LSPI.B
Example of piston damage due to an LSPI event observed during the testing of a competitors motor oil. The red arrows indicate sections of the ring land that have broken away from the piston.
BBased on zero LSPI events in five consecutive tests of AMSOIL Signature Series, XL and OE 5W-30 Motor Oil in the LSPI engine test required by the GM dexos1 Gen 2 specification.
Signature Series Resists Viscosity Increase
Signature Series is barely challenged by the industry-standard testing, demonstrating only a 0.1% viscosity inc