Signature Series 5W-40 100% Synthetic Max-Duty Diesel Oil
Signature Series 5W-40 100% Synthetic Max-Duty Diesel Oil is AMSOIL's top-grade 100% synthetic diesel oil — 6X better wear protection than required by the Detroit Diesel DD13 scuffing test, with reserve protection that lets serious diesel owners extend drain intervals with confidence.1
Why this product
- 6X better engine wear protection than required by the Detroit Diesel DD13 scuffing test.1
- Reserve protection — the option to extend drain intervals with confidence.
- Withstands high-temperature breakdown under heavy use in extreme temperatures; advanced synthetic technology for maximum fuel economy.
- Exceeds the latest API CK-4 specification.
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Become a Preferred Customer →Signature Series 5W-40 100% Synthetic Max-Duty Diesel Oil — FAQ
No — synthetic oils do not cause engines to leak. AMSOIL diesel oils are fully compatible with modern seal materials and are formulated to condition seals, keeping them pliable. They're safe in both new and high-mileage engines.
Both exceed the API CK-4 specification. Heavy-Duty delivers 4X better wear protection than required by the Detroit Diesel DD13 scuffing test; Signature Series Max-Duty delivers 6X, with reserve protection that allows extended drain intervals — it's the pick for hardcore enthusiasts and owners who want the best.
Signature Series Max-Duty is suitable for applications specifying API SN+ and earlier, making it ideal for mixed fleets. Check your owner's manual for the specified viscosity and rating.
Keep reading
1 Wear-protection comparisons are based on the requirements of the Detroit Diesel DD13 scuffing test. Price shown is AMSOIL's current online retail price, synced weekly. Checkout completes on amsoil.com; orders are sold, shipped and fulfilled by AMSOIL Inc. Tuned Yota is an Authorized AMSOIL Dealer.