AMSOIL 15W-40 Heavy-Duty Diesel and Marine Oil

  • Recommended for applications specifying API CI-4+ and prior specifications
  • Controls soot and wear
  • Reduces oil consumption and emissions
  • Delivers maximum engine protection over extended drain intervals
  • Provides outstanding protection and performance in temperature extremes
  • Try Signature Series Max-Duty 15W-40 for a serious upgrade

Product Overview

Premium diesel oil providing excellent performance in diesel engines where highly effective control of wear and deposits is vital. Built with heavy-duty dispersant/detergent additives with 12 TBN, Synthetic Heavy-Duty Diesel & Marine Oil neutralizes acids and controls soot thickening from EGR and blow-by to protect against corrosion, cylinder bore polishing (wear) and varnish/sludge deposits. It resists heat and breakdown and is formulated for extended drain intervals.

CONTROLS SOOT AND WEAR

  • Neutralizes acids and controls soot thickening to protect against corrosion, wear, varnish and sludge deposits
  • Reduces oil consumption and emissions
  • Delivers maximum engine protection over extended drain intervals

EXCELS IN EXTREME TEMPERATURES

  • Provides outstanding protection and performance in temperature extremes
  • Resists heat and breakdown better than conventional oils
  • Eases cold-weather starting and provides vital startup lubrication

Ready to buy or need help selecting the right product?

 

Product information checked: September 2026. Product formulations, specifications, applications, availability and published claims can change.
For the latest official information, consult the AMSOIL Corproate Website.

Current AMSOIL Promos
Upcoming Shows
The 10th Annual Field of Dreams Car Show
The 10th Annual Field of Dreams Car Show
Nov. 21-22, 2026 | Florida Classic Park | Brooksville, Florida ...
Blog & News
AMSOIL Expands Off-Road Racing Support with CORR
AMSOIL Expands Off-Road Racing Support with CORR
AMSOIL expands its grassroots racing support as presenting sponsor of CORR for 2026–2027, bringing short-course off-road competition to the Southwest ...
Event Coverage Spotlight
26th Annual Mustang & Ford Roundup
26th Annual Mustang & Ford Roundup
Feb. 16, 2013 | Waterford Lakes Town Center | Orlando, Florida ...
Facts & Info Spotlight
Oils Against Oils
Oils Against Oils
Originally published in Fast Fours & Rotaries in July 1998, “Oils Against Oils” reports a performance-car engine test comparing synthetic ...
Heritage Spotlight
Moving On to an SUV
Moving On to an SUV
2002 Chevy Trailblazer LTZ 

I started wanting a truck but wasn’t ready for a Suburban or Escalade size, and I was ...