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DOMINATOR 20W-50 Competition Diesel Oil (DCO)

 DOMINATOR 20W-50 Competition Diesel Oil (DCO)
Product Code: DCO • Brand: AMSOIL

AMSOIL DOMINATOR® 20W-50 Competition Diesel Oil is designed for professionals and enthusiasts who want a step up in diesel protection. It is specifically designed for high-horsepower diesel engines and delivers the benefits most important to diesel competitors, including robust durability, outstanding bearing protection and the ability to withstand the extreme pressures and temperatures common to diesel competition.

Package sizes include:

1-Quart Bottle
1-Gallon Bottle

See Pricing or Place an Order
MSDSData Sheet

Product Details

Product Applications

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

Product Application Specs

• 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

Product Description

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

ASTM-D5481 Test results

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.


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.


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.

1Refer to your owner's manual for OEM drain interval recommendations and guidelines for severe and normal service.

diesel oil OfficialOil icon


This product is not expected to cause health concerns when used for the intended application and according to the recommendations in the Material Safety Data Sheet (MSDS).

Click here to view the MSDS Data Sheet for AMSOIL DCO.

Keep out of the reach of children. Don't pollute. Return used oil to collection centers.

Technical Data

DOMINATOR® 20W-50 Competition Diesel Oil (DCO)
Kinematic Viscosity @ 100°C, cSt (ASTM D-445)18.5
Kinematic Viscosity @ 40°C, cSt (ASTM D-445)137.5
Viscosity Index (ASTM D-2270)151
CCS Viscosity @ -20°C, cP (ASTM D-5293)4118 (-15)
Pour Point °C (°F) (ASTM D-97)-37 (-35)
NOACK Volatility, % weight loss (g/100g) (ASTM D5800)3.7
Total Base Number (ASTM D2896)10.1
High-Temperature/High-Shear Viscosity, cP (ASTM D5481)5.5
Sulfated Ash Content, wt. % 1.0

Related Videos

Diesel Power Challenge

 DOMINATOR 20W-50 Competition Diesel Oil (DCO)

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