Proven Protection

Excessive wear to diesel cylinder liners and rings leads to increased oil consumption and loss of compression, reducing horsepower and fuel economy.
Independent testing shows AMSOIL Signature Series Max-Duty Synthetic Diesel Oil provides 6X more wear protection than required by Detroit Diesel’s standard*. In the same test, AMSOIL Heavy-Duty Synthetic Diesel Oil delivers 4X more protection against wear than required by the standard*.
Detroit Diesel, a leader in diesel engine technology, sets a standard for measuring cylinder liner and ring wear with its DD13 Scuffing Test for the DFS 93K222 specification. Testing of AMSOIL synthetic diesel oils was conducted by an independent lab in accordance with the following parameters:
The test simulates real-world use with a modified Detroit Diesel DD13 diesel engine running for 200 hours. Cylinder liner scuffing and top ring wear are measured and used oil analysis is performed to determine wear levels during the test.
With our top-grade synthetic diesel oils under your hood, you can be confident that there’s more than enough protection to handle the demands of your performance modifications and keep your diesel running strong in the most severe conditions.
*Detroit Diesel DD13 Scuffing Test for Specification DFS 93K222
Professional Racers Trust AMSOIL

Ben Shadday
Done Right Diesel
'The rod bearings, everything looked great. We did have one crank bearing that wasn’t bad, but it showed some wear, and rightfully so. The power level we’re at, that’s kind of what we were after. We want to know, do we need to schedule a maintenance halfway through the season. The cam looked great. The tappets looked good. There was no concern with either piece there. The protection is definitely there.'
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Signature Series Max-Duty Synthetic Diesel Oil
- 6X more engine protection than required by a leading industry standard1
- Ultimate engine cleanliness and efficiency
- Outstanding acid neutralization for long-term engine protection
- Top-grade protection for extended drain intervals
- Available in 5W-30, 0W-40, 5W-40 and 15W-40 viscosities
Heavy-Duty Synthetic Diesel Oil
- 4X more engine protection than required by a leading industry standard1
- Excellent engine cleanliness and efficiency
- Outstanding acid neutralization for long-term engine protection
- Outstanding protection for OEM-recommended drain intervals
- Available in 10W-30, 5W-40 and 15W-40 viscosities
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