AMSOIL DOMINATOR® 20W-50 COMPETITION DIESEL OIL

AMSOIL DOMINATOR 20W-50 Competition Diesel Oil is a purpose-built synthetic diesel oil engineered for high-horsepower, performance-modified diesel engines used in sled pulls, drag racing, and dyno competition. It delivers 50% more film thickness than the 3.5 cP HTHS minimum required for SAE 15W-40 oils, providing a measurable step up in bearing and cylinder wall protection when the stakes are highest.

Competition diesel engines operate in a different world than daily drivers. Modified Cummins, Duramax, and Power Stroke engines tuned for maximum horsepower and torque generate extreme cylinder pressures and shearing forces that can break down conventional oils in a single pass. Fuel dilution from high-volume fueling further thins the oil, and turbocharger shaft temperatures can push lubricants past their thermal limits. Standard 15W-40 diesel oils were never designed for this kind of abuse.

50% MORE FILM THICKNESS FOR EXTREME BEARING LOADS
When you're pushing 800, 1,000, or 1,500+ horsepower through a competition diesel, bearing loads increase dramatically. Thin oil film means metal-to-metal contact, scuffing, and eventual failure. DOMINATOR 20W-50 Competition Diesel Oil delivers a High-Temperature/High-Shear (HTHS) viscosity of 5.5 cP (ASTM D5481), which is 50% above the 3.5 cP HTHS limit for SAE 15W-40 oils. That additional film thickness directly translates to better protection for rod bearings, main bearings, and wrist pins under extreme cylinder pressures. The formulation is also heavily fortified with zinc and phosphorus anti-wear additives to guard against scuffing in the most severe conditions.

RESISTS VISCOSITY LOSS FROM FUEL DILUTION
High-horsepower diesel builds push significantly more fuel than stock engines. That excess fuel inevitably makes its way past piston rings and into the crankcase, diluting the oil and reducing its viscosity. Thinner oil means less protection right when the engine needs it most. DOMINATOR 20W-50 starts with a robust viscosity baseline, with a kinematic viscosity of 18.5 cSt at 100°C and 135.5 cSt at 40°C. That heavier starting point gives the oil room to absorb fuel dilution while still maintaining a protective viscosity film over critical components. The NOACK Volatility result of 3.7% weight loss (ASTM D5800) also confirms the oil resists evaporative losses at high temperatures, keeping it in grade longer.

PROTECTS TURBOCHARGERS FROM THERMAL BREAKDOWN
Competition turbo diesel setups generate punishing exhaust gas temperatures that transfer directly into the turbocharger bearing housing. Oil that breaks down under this heat forms deposits on the turbo shaft and bearing surfaces, restricting oil flow and eventually causing reduced boost or catastrophic turbo failure. DOMINATOR 20W-50 is formulated with maximum levels of oxidation-inhibitor additives to resist thermal degradation and deposit formation. The durable 20W-50 synthetic base provides the thermal stability needed to survive the heat cycling that competition turbos experience during runs and cool-down.

BROAD SPECIFICATION COVERAGE FOR MODIFIED DIESEL BUILDS
DOMINATOR 20W-50 Competition Diesel Oil meets API CK-4, CJ-4, CI-4+, and CH-4 specifications. It also satisfies 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, and Ford WSS-M2C171-F1. This makes it a direct fit for competition-modified Cummins 5.9L and 6.7L engines, Ford 6.0L and 6.7L Power Stroke builds, and other turbocharged diesel platforms commonly seen in truck pulling and diesel drag racing. It is compatible with both conventional and synthetic engine oils, though mixing will reduce performance benefits and AMSOIL does not support extended drain intervals where oils have been mixed. Aftermarket oil additives are not recommended.

SERVICE LIFE
DOMINATOR Competition Diesel Oil provides lasting protection for multiple competition events. Use oil analysis to determine the appropriate drain interval for your specific engine and application. When not competing, follow OEM drain interval recommendations or extend drain intervals based on oil analysis results. Refer to your owner's manual for OEM guidelines covering both severe and normal service.