DOMINATOR® vs. Signature Series: What’s the Best AMSOIL Diesel Oil for Your Rig?

Not all diesel oil is created equal — especially when you're talking AMSOIL. If you're choosing between DOMINATOR® Competition Diesel Oil and Signature Series Max-Duty Diesel Oil, the best option comes down to how you drive — not just what you drive.

Let’s break it down so you can make the right call for your engine.

🧡 DOMINATOR®: Built for the Track, the Pull, and the Power

DOMINATOR® Competition Diesel Oil is engineered for one thing: high horsepower competition environments. If you're running:

• Sled pulling rigs

• Drag racing diesels

• Modified off-road trucks

…this is your oil.

Key Benefits:

✔️ Boosted zinc for extreme wear protection under max load
✔️ SAE 20W-50 weight offers thick film strength at high temps
✔️ Designed for short-interval oil changes in high-stress builds

Important Note:
DOMINATOR isn’t made for extended drain intervals — this is a specialty product, not an everyday driver’s oil.

Whether competing in sled pulls, drag races or dyno challenges, competitors using DOMINATOR Competition Diesel Oil enjoy the confidence and security that come with providing their diesel trucks maximum protection and performance.

Wear Protection
Racing and high-performance diesel engines are modified to deliver maximum horsepower and torque. Their powerful designs create shearing forces that can cause oils to lose viscosity, leaving bearings, pistons and other components vulnerable to wear and failure. DOMINATOR 20W-50 Competition Diesel Oil delivers 50 percent more film thickness* to withstand high cylinder pressures and protect against wear. It is heavily fortified with zinc and phosphorus anti-wear additives to provide additional protection against scuffing and wear in severe conditions.

*compared to the 3.5cP HTHS limit for SAE 15W-40

Viscosity Control
High-horsepower diesel engines push a lot of fuel, leading to fuel dilution. Fuel reduces the oil's viscosity. As the oil becomes thinner, it compromises the lubrication of critical components, increasing wear. DOMINATOR Competition Diesel Oil's robust formulation helps offset the damaging effects of fuel dilution by maintaining its protective viscosity longer.

Withstands Turbocharger Heat
Over time, turbos can suffer reduced performance or catastrophic failure. DOMINATOR Competition Diesel Oil is designed with an extremely durable 20W-50 synthetic formulation that contains maximum levels of oxidation-inhibitor additives to resist harmful oxidation and provide exceptional resistance to deposit formation, preserving turbocharger performance and life.

APPLICATIONS
Use in performance-modified diesel engines that require any of the following specifications:

• API CK-4, CJ-4, CI-4+, CH-4
• Cummins 20081/20086
• Mack EO-O/EOS-4.5
• Volvo VDS3/VDS4/VDS4.5
• Caterpillar ECF-2, ECF-3, ECF-1-a
• Renault RLD-3/RLD-4
• Chrysler MS 10902
• Ford WSS-M2C171-F1

COMPATIBILITY
DOMINATOR 20W-50 Competition Diesel Oil is compatible with other conventional and synthetic engine oils. Mixing AMSOIL diesel oils with other oils, however, will shorten the oil's life expectancy and reduce the 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 diesel oils.

SERVICE LIFE
DOMINATOR Competition Diesel Oil provides lasting protection for multiple events. Use oil analysis to determine appropriate drain interval.

Note: When not competing, follow OEM¹ drain intervals or extend drain intervals with oil analysis.

🔴 Signature Series Max-Duty: The Daily Workhorse Champion

If your diesel is your livelihood — think hotshot towing, long-haul driving, or heavy-duty commuting — you need Signature Series Max-Duty Diesel Oil.

This oil protects your engine like nothing else on the road, with features like:
✔️ Up to 3X longer drain intervals than OEM
✔️ Industry-leading soot and wear control
✔️ Cold-start protection + stability in extreme heat
✔️ Available in viscosities like 5W-40, 15W-40, 10W-30, and more

Max-Duty is ideal for:

• Powerstroke, Duramax, or Cummins daily drivers

• Tow rigs pulling trailers or equipment

• Fleet trucks and over-the-road diesels

• High-mileage diesel owners looking for long-term protection

Protects Against Rust

Provides up to 2X better rust protection.^K

AMSOIL Fights Wear

AMSOIL delivers powerful engine protection. How good is it? In third-party testing compared to a leading brand, AMSOIL provided long-lasting wear protection, keeping cylinder liners looking like new.^DD

Delivers More Wear Protection

Third-party testing shows Signature Series Max-Duty Synthetic Diesel Oil delivers 6X more protection against wear than required by Detroit Diesel’s* standard.^II

^IIBased on third-party testing in the Detroit Diesel DD13 Scuffing Test for specification DFS 93K222 using 5W-30 as worst-case representation.
*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.

Keeps Turbos Clean

AMSOIL Signature Series Max-Duty Synthetic Diesel Oil provides protection boosted to the max, delivering up to 60% better turbo cleanliness^J and withstanding the extra demands you place on the turbo when pulling heavy loads or updating the tune for maximum horsepower.

^JBased on specification standards of CAT C13 2nd Ring Top Land Carbon testing

VISCOSITY CONTROL

• Resists oxidation and the thickening effects of soot contamination
• Retains viscosity after high-temperature service for maximum engine protection and efficiency
• Provides up to 76 percent less oil consumption⁵

⁵Than required by the API CK-4 standard in the Caterpillar-1N oil consumption test

Reduces Oil Consumption

Signature Series Max-Duty Synthetic Diesel Oil provides up to 76% less oil consumption.^L

🛠️ So, Which One’s Right for You?

Still not sure? That’s what I’m here for.

🔧 Ask the Right Questions. Use the Right Oil.

At AC Oil & Supply, I don’t believe in just selling oil. I believe in helping you choose the right oil for your build, your goals, and your engine’s health.

👉 Message me directly or use my referral number #30482874 at AMSOIL.com to support this local Central Texas dealer.

Or give me a call/text: 512-818-0299

Email: orders@acoilsupply.com

📦 Ask about current promos — free hat and double rewards are in rotation right now!