About this item

• Product Overview

  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.

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

  HEALTH & SAFETY
  This product is not expected to cause health concerns when used for the intended application and according to the recommendations in the Safety Data Sheet (SDS). An SDS is available online at www.amsoil.com or upon request at (715) 392-7101. Keep Out of Reach of Children. Recycle used oil and bottle.

  AMSOIL PRODUCT WARRANTY
  AMSOIL products are backed by a Limited Liability Warranty. For complete information visit www.amsoil.com/warranty/.

  * 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. All products advertised here are developed by AMSOIL for use in the applications shown.

• Technical Specifications
  Data Bulletin

  Data Bulletins

  Warranty

  WARRANTY

  SDS

  SDS

  
  
  
• Product Reviews
  5 star rating

  Based on 14 reviews

  Based on 14 reviews

  See all customer reviews

  Sort by

  Most Recent Most Helpful Highest Rating Lowest Rating Oldest

  • 5 star rating
    A soul dominator
    By  SCOTT,  a  Verified Buyer  on  March 22, 2026

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    Love the oil just wish the price was better. Maybe offer in larger quantity
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (1) NO (0)
  • 5 star rating
    The best oil I have ever ran in my LMM
    By  DEMETRE,  a  Verified Buyer  from  Colorado  on  December 06, 2025

    Open report issue form

    Describe the issue

    Cancel Submit
    Towing, Hauling, Daily Driving, etc etc. I have a very high milage LMM and this oil holds its viscosity like no other in the summertime extreme temps. I have zero issues staying with this oil in the winter months as well. I highly recommend.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (2) NO (0)
  • 5 star rating
    Very good oil
    By  ROBERT,  a  Verified Buyer  from  Ohio  on  February 14, 2025

    Open report issue form

    Describe the issue

    Cancel Submit
    Thus stuff is amazing , I use it in my pulling truck (cummins) and it has never failed me !
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    20W50 competition diesel oil
    By  RICHARD,  a  Verified Buyer  from  Georgia   on  October 24, 2024

    Open report issue form

    Describe the issue

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    This oil lowered my oil temps by 8-9 degrees Fahrenheit, and is heavy enough that none comes out of my crankcase tube. If your diesel has a little extra crankcase pressure I HIGHLY recommend this oil.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (1) NO (0)
  • 5 star rating
    20W-50 Competition Oil
    By  Bill,  a  Verified Buyer  from  NE NC  on  December 14, 2023

    Open report issue form

    Describe the issue

    Cancel Submit
    I use this oil in my GM 6.6 diesel and I really like the added protection during our very hot summers.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    A+
    By  PAUL,  a  Verified Buyer  from  Massachusetts   on  October 28, 2023

    Open report issue form

    Describe the issue

    Cancel Submit
    Only only I run in my race truck and my old IDI’s. I
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    Oil
    By  RAYMOND,  a  Verified Buyer  on  September 27, 2023

    Open report issue form

    Describe the issue

    Cancel Submit
    Fast service
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    A+
    By  PAUL,  a  Verified Buyer  from  Massachusetts   on  July 07, 2023

    Open report issue form

    Describe the issue

    Cancel Submit
    This is the only oil I run in my race Duramax, pulling 12v and my old daily idi 6.5. Never a issue and always good test results
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (1) NO (0)
  • 5 star rating
    20W50 for new GM 6.6L Diesels
    By  WILLIAM,  a  Verified Buyer  from  Camden, NC  on  January 08, 2022

    Open report issue form

    Describe the issue

    Cancel Submit
    This is very good oil for GM diesels. The current engine has a crankshaft relate noise at normal operating temp (NOT), I believe due to an inferior oil pump design. Below 31PSI, a crankshaft related noise is discernable. I have written GM on possible solutions that are cheaper than replacing the engine under warranty. The 20W50 helps keep the oil pressure above 32PSI at idle which stops the noise. In the colder months I have cut the oil 50/50 with 15W40 DME, but once at NOT, the crankshaft noise does come back. This engine seems to need 30W oil to prevent the noise at NOT at idle. I am unable to find a good 30W diesel oil with API CI-4 or CK-4. The 20W50 from AMSOIL is the best at helping this situation until they make a 30W or 30W40 for this engine.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (2) NO (0)
  • 5 star rating
    Damaged leaking container no response from Amsoil
    By  BARRY,  a  Verified Buyer  from  Sonora Ca  on  November 25, 2021

    Open report issue form

    Describe the issue

    Cancel Submit
    The product is great and I have ordered many times. My last order arrived with a punctured leaking container. Tried to contact Amsoil with photos but received NO response. Could do much better with customer service.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (2) NO (1)

• Highlights

  The Confidence to Compete, The Protection To Win

  • Specifically designed for high-HP diesel engines
  • Outstanding bearing protection under extreme loading
  • Delivers 50% more film thickness¹
  • Robust viscosity control

  ¹compared to the 3.5cP HTHS limit for SAE 15W-40

• Returns

  We offer easy returns for customers. If your product is unused and unopened, you may return it within 30 days for a full refund of the purchase price. View full AMSOIL Return Policy.

• Payments

  We accept Visa, Mastercard, American Express, Discover and PayPal, and provide secure checkout and encrypted payment processing.

• Product Overview

  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.

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

  HEALTH & SAFETY
  This product is not expected to cause health concerns when used for the intended application and according to the recommendations in the Safety Data Sheet (SDS). An SDS is available online at www.amsoil.com or upon request at (715) 392-7101. Keep Out of Reach of Children. Recycle used oil and bottle.

  AMSOIL PRODUCT WARRANTY
  AMSOIL products are backed by a Limited Liability Warranty. For complete information visit www.amsoil.com/warranty/.

  * 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. All products advertised here are developed by AMSOIL for use in the applications shown.

• Technical Specifications
  Data Bulletin

  Data Bulletins

  Warranty

  WARRANTY

  SDS

  SDS

  
  
  
• Product Reviews
  5 star rating

  Based on 14 reviews

  Based on 14 reviews

  See all customer reviews

  Sort by

  Most Recent Most Helpful Highest Rating Lowest Rating Oldest

  • 5 star rating
    A soul dominator
    By  SCOTT,  a  Verified Buyer  on  March 22, 2026

    Open report issue form

    Describe the issue

    Cancel Submit
    Love the oil just wish the price was better. Maybe offer in larger quantity
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (1) NO (0)
  • 5 star rating
    The best oil I have ever ran in my LMM
    By  DEMETRE,  a  Verified Buyer  from  Colorado  on  December 06, 2025

    Open report issue form

    Describe the issue

    Cancel Submit
    Towing, Hauling, Daily Driving, etc etc. I have a very high milage LMM and this oil holds its viscosity like no other in the summertime extreme temps. I have zero issues staying with this oil in the winter months as well. I highly recommend.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (2) NO (0)
  • 5 star rating
    Very good oil
    By  ROBERT,  a  Verified Buyer  from  Ohio  on  February 14, 2025

    Open report issue form

    Describe the issue

    Cancel Submit
    Thus stuff is amazing , I use it in my pulling truck (cummins) and it has never failed me !
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    20W50 competition diesel oil
    By  RICHARD,  a  Verified Buyer  from  Georgia   on  October 24, 2024

    Open report issue form

    Describe the issue

    Cancel Submit
    This oil lowered my oil temps by 8-9 degrees Fahrenheit, and is heavy enough that none comes out of my crankcase tube. If your diesel has a little extra crankcase pressure I HIGHLY recommend this oil.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (1) NO (0)
  • 5 star rating
    20W-50 Competition Oil
    By  Bill,  a  Verified Buyer  from  NE NC  on  December 14, 2023

    Open report issue form

    Describe the issue

    Cancel Submit
    I use this oil in my GM 6.6 diesel and I really like the added protection during our very hot summers.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    A+
    By  PAUL,  a  Verified Buyer  from  Massachusetts   on  October 28, 2023

    Open report issue form

    Describe the issue

    Cancel Submit
    Only only I run in my race truck and my old IDI’s. I
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    Oil
    By  RAYMOND,  a  Verified Buyer  on  September 27, 2023

    Open report issue form

    Describe the issue

    Cancel Submit
    Fast service
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (0) NO (0)
  • 5 star rating
    A+
    By  PAUL,  a  Verified Buyer  from  Massachusetts   on  July 07, 2023

    Open report issue form

    Describe the issue

    Cancel Submit
    This is the only oil I run in my race Duramax, pulling 12v and my old daily idi 6.5. Never a issue and always good test results
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (1) NO (0)
  • 5 star rating
    20W50 for new GM 6.6L Diesels
    By  WILLIAM,  a  Verified Buyer  from  Camden, NC  on  January 08, 2022

    Open report issue form

    Describe the issue

    Cancel Submit
    This is very good oil for GM diesels. The current engine has a crankshaft relate noise at normal operating temp (NOT), I believe due to an inferior oil pump design. Below 31PSI, a crankshaft related noise is discernable. I have written GM on possible solutions that are cheaper than replacing the engine under warranty. The 20W50 helps keep the oil pressure above 32PSI at idle which stops the noise. In the colder months I have cut the oil 50/50 with 15W40 DME, but once at NOT, the crankshaft noise does come back. This engine seems to need 30W oil to prevent the noise at NOT at idle. I am unable to find a good 30W diesel oil with API CI-4 or CK-4. The 20W50 from AMSOIL is the best at helping this situation until they make a 30W or 30W40 for this engine.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (2) NO (0)
  • 5 star rating
    Damaged leaking container no response from Amsoil
    By  BARRY,  a  Verified Buyer  from  Sonora Ca  on  November 25, 2021

    Open report issue form

    Describe the issue

    Cancel Submit
    The product is great and I have ordered many times. My last order arrived with a punctured leaking container. Tried to contact Amsoil with photos but received NO response. Could do much better with customer service.
    Bottom Line

    Yes, I would recommend this to a friend.
    Was this review helpful?

    YES (2) NO (1)