Why Buy Signature Series?

There are many big names out there. A lot of new start-ups claiming to be the Holy Grail in engine oil. But in short, AMSOIL remains on top for one reason – the founder AJ Amatuzio wanted to provide a product where the customer can be certain he (or she) is getting what is expected.  Nothing is scaled down to improve profit margins. (There are no share holders) Simply the best and that process involves earning the highest respect from suppliers for the privilege of developing the finest finished lubricants.

Setting Standards For You to Measure From

Signature Series Synthetic Motor Oil is not only the best oil we have ever made, it’s better than any competitive oil we have tested. Advanced engine technology and the normal demands of everyday life generate extreme conditions that can challenge motor oil and engine life. Signature Series delivers the ultimate protection against everyday extremes like towing and extended idling. Don’t just take our word for it; read on for proof.

Do you drive in hot temperatures?

In testing, kept pistons clean and held oil thickening to only 6 percent, a minimal amount compared to the proposed specification limit of 150 percent4. 50 percent more detergents5 to help keep oil passages clean and promote oil circulation. Provides 90 percent better protection against sludge6.

Do you have long commutes?

30 percent more acid-neutralizing power8 than Mobil 1*, and 36 percent more than Royal Purple*, helping engines stay cleaner, longer. Reserve protection, so you can go up to 25,000 miles, 700 hours of operation or one year between oil changes, whichever comes first.

Does your vehicle have a turbocharger?

72 percent better turbocharger protection than required2 by the GM dexos1® Gen 2 specification. Achieved 100 percent protection against low-speed pre-ignition (LSPI)3.

Do you tow or haul?

75 percent more engine protection against horsepower loss and wear7.

Do you drive in cold temperatures?

66 percent better cold-temperature performance for easier starting, better fuel economy, improved oil flow and reduced wear.

Do you want extra engine protection?

Far superior wear protection compared to the competition – kept bearings looking like new after 100,000-mile test1.


1Testing 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. 2Based on independent testing of AMSOIL Signature Series 5W-30 in the GM turbo coking test. 3Based on zero LSPI events in five consecutive tests of AMSOIL Signature Series 5W-30 Motor Oil in the LSPI engine test required by the GM dexos1 Gen 2 specification.  4Based on the ILSAC GF-5 PLUS specification. 5vs. AMSOIL OE Motor Oil 6Based 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. 7Based on independent testing of AMSOIL Signature Series 0W-20, in ASTM D6891 as required by the API SN specification. 8Based upon independent testing of Mobil 1 Annual Protection Full Synthetic 5W-30, Royal Purple High Performance 5W-30 and AMSOIL Signature Series 5W-30 in ASTM D2896. Oils purchased 05/03/18. *All trademarked names 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.