Midwest Synthetic AMSOIL Dealer

AMSOIL Signature Series Synthetic Motor Oil Excels in Double-Length Performance Test

The Sequence IIIG Engine Test (ASTM D7320) is designed to evaluate automotive motor oils for oil thickening, piston deposits, oil consumption and engine wear during moderately high-speed, high-temperature service. It must be passed for motor oil to meet the API SN and ILSAC GF-5 motor oil specifications. Results in the 100-hour test are an important indicator of how well a motor oil will perform in real-world service. Because Signature Series has historically performed well in the test, AMSOIL decided to push the envelope and subject the oil to a double-length (200-hour) Sequence IIIG Engine Test. Signature Series 5W-30 Synthetic Motor Oil not only passed the double-length test, it did so with flying colors. Results show the oil delivered outstanding wear protection, deposit control and oxidative stability after 200 hours of testing. AMSOIL is not aware of another motor oil that has passed a double-length Sequence IIIG Engine Test.

Shop for Signature Series Synthetic and other gasoline engine oil now in the on-line store!

Converting to Synthetic

Convert to AMSOIL Synthetic oil

Enjoy reduced maintenance, better fuel economy and longer equipment life. Synthetic oil is superior. Click here for more information on converting to synthetic oil.


Diesel Engine Oils

AMSOIL synthetic diesel oils are formulated with premium synthetic technology and robust additive packages, providing vehicles and equipment with the protection they need to stay on the job longer and perform their best.


Signature Series Max-Duty Synthetic Diesel Oil 5W-40


Protect your investment in diesel power and confidently extend drain intervals with our top-grade synthetic diesel oil. AMSOIL Signature Series Max-Duty Synthetic Diesel Oil delivers 6X better wear protection than required by the Detroit Diesel DD13 Scuffing Test for Specification DFS 93K222. Advanced synthetic technology provides excellent viscosity control and outstanding extreme-temperature performance, while minimizing oil consumption. The result: protection that’s boosted to the max.

Shop for Max-Duty Synthetic and other AMSOIL Diesel Oils

Transmission Fluid

Transmissions in commercial vehicles, SUVs, trucks and vans – particularly those used for hauling or towing – are subjected to severe-service operation and increased heat. Elevated temperatures cause fluids to break down, allowing damaging metal-to-metal contact and the formation of sludge and deposits. The problem is worse in modern transmissions with more gears, clutch packs and narrow oil passages that require clean, high-quality fluid to achieve maximum performance and life. AMSOIL Signature Series Synthetic Automatic Transmission Fluid is specifically formulated to withstand the rigors of heavy towing, elevated temperatures and challenging terrain. It remains fluid in sub-zero temperatures and provides reserve protection during heavy use and even abuse.

Your transmission is one of the most neglected, and complex (say expensive) components of your vehicle. If your search for overlooked car maintenance online, every list will contain transmission fluid changes. Check out the Tech Talk article Proactively Service your Transmission to learn why this maintenance is so important for todays vehicles and can save thousands of dollars in repairs later.

Shop for AMSOIL Transmission fluid

Synthetic Small Engine oils for 4 stroke and 2-stroke equipment



AMSOIL 4-stroke and 2-stroke lubricants for your outdoor power equipment! Learn more about small engine oil.


Gear Lubes

SEVERE GEAR is designed for those who demand the best. Engineered with high film strength for high-load demands. Reduces friction and provides the ultimate protection against wear. Excels in extreme temperatures. Helps maintain efficiency and outperforms conventional gear oils. Excellent for all cars and trucks, but especially well-suited for towing, hauling, racing, commercial use or other severe duty.

Check out the gear-lube page to learn more about gear lubes.

Shop for AMSOIL Gear Lube