5W-40 Engine Oil
Premium 5W-40 Engine Oil for Diesel and European Applications
Built for confidence in any season, 5W-40 engine oil delivers smooth cold starts and steadfast protection at operating temperatures. Backed by rigorous testing, Hot Shot’s Secret helps you protect your investment. We formulated this product for hardworking diesels and refined it for European engines.
What Is 5W-40 Engine Oil?
5W-40 Diesel engine oil is a 100% synthetic engine oil infused with FR3® Nano Lubricant Technology. It was developed for heavy-duty protection and will not void your manufacturer’s warranty.
For European applications, Hot Shot’s Secret Gray Diamond European Spec full synthetic features Group III base oils and an emissions-safe detergent that helps keep turbochargers cool and free from deposits. It is safe for DPF and TWC systems and meets the requirements of many European manufacturers.
Understanding 5W-40 Viscosity Ratings
5W-40 synthetic oil flows like a lower-viscosity oil in cold conditions, facilitating easier starts, while maintaining a thick protective coating at operating temperatures.
At a glance, this oil’s viscosity ratings mean:
- 5W: The formula flows quickly in cold temps for reliable cold starts.
- 40: It maintains a thicker oil film in high temperatures and under heavy load.
Multigrade oil is ideal for year-round performance and engine durability — delivering rapid oil circulation on startup, while preserving film strength when hot.
Common Use Cases for 5W-40
Many modern diesel and European-spec engines specify 5W-40.
Common uses for this formulation include:
- Diesel pickup trucks and Class 8 semis
- Fleets operating in extreme weather conditions
- Turbocharged or high-RPM engines
- Light-duty European diesel or gasoline vehicles that call for mid-SAPS oils
Explore Our Lineup of 5W-40 Engine Oils
Hot Shot’s Secret range of premium, fully synthetic 5W-40 engine oil — infused with FR3 Nano Technology — delivers peak performance across demanding diesel and European applications. Formulated with advanced synthetic base stocks, these oils help clean and protect engines and support extended service intervals.
We offer three scientifically tested 5W-40 engine oils to keep your engine running smoothly year-round.
Green Diamond Fleet 5W-40 Synthetic Diesel Oil
Our Green Diamond Fleet Oil is formulated to meet the demands of severe operating conditions.
Best for: Mixed diesel fleets, severe-duty, stop-and-go operations
Base oil: 100% Group III synthetic
Highlights:
- – Improves starting in cold weather vs. conventional oils
- – Lowers oil consumption by 78% (compared to CJ-4 oils)
- – Limits wear by 71%
- – Improves power, fuel economy by up to 3% and enhances oxidation stability
- – Handles soot 46% more effectively than CJ-4 oils
- – Reduces DPF clogging and extends engine, turbo and injector life
- – Meets API CK-4 and Ford WSS-M2C171-F1 specifications
Green Diamond Fleet 5W-40 synthetic diesel oil is ideal for heavy loads, dusty environments and extended intervals.
Blue Diamond PAO 5W-40 Synthetic Diesel Oil
Looking for the best 5W-40 oil for diesel engines? Hot Shot’s Secret Blue Diamond PAO 5W-40 heavy-duty oil is a full PAO synthetic formula engineered for heavy-duty protection and year-round performance.
Best For: High-performance, high-heat, long-interval diesel engines
Base Oil: Group IV and V (100% PAO + ester)
Highlights:
- – Reduces wear by 71% and significantly lowers oil consumption
- – Supports extended oil life (50,000 to 100,000 miles) with TBN monitoring
- – Provides high-RPM/turbo stability
- – Maintains integrity under extreme loads and heat
- – Meets API CK-4 and Ford WSS-M2C171-F1 specifications
Blue Diamond PAO 5W-40 synthetic diesel oil is ideal for over-the-road haulers, heavy-duty applications and performance enthusiasts. It is compatible with modern emissions systems, including DPF, EGR and SCR components.
Gray Diamond 5W-40 European Spec Synthetic Oil
Gray Diamond Euro Engine Oil is built to protect turbocharged gas and diesel engines, delivering clean performance and reliability in modern European applications.
Best For: Light-duty European diesel and gasoline engines
Base Oil: Group III Synthetic
Highlights:
Mid-SAPS formulation for modern European specs
- – Protects turbochargers and emissions systems
- – Exceeds API SN and meets OEM Euro standards (Mercedes-Benz, VW, BMW, etc.)
- – Provides excellent heat resistance and deposit control
- – Supports long European drain intervals
Gray Diamond 5W-40 European-spec synthetic oil is ideal for Audi, VW, BMW, Mercedes, Porsche and more.
What Makes Our 5W-40 Oils Different?
Hot Shot’s Secret 5W-40 engine oils set the gold standard by pairing FR3 Nano Technology with standards-driven chemistry — resulting in lower friction and temperatures, cleaner operation and protection proven in real-world testing. FR3 reduces wear and boosts efficiency while meeting rigorous CK‑4/API SN or Euro OEM specs and supporting longer service with oil analysis and TBN management.
Discover the Power of FR3® Friction Reducer
Our proprietary nano lubricant offers several benefits:
- – Reduces friction and metal-to-metal contact
- – Lowers operating temperatures
- – Improves fuel efficiency and horsepower
- – Minimizes wear on pistons, camshafts, and bearings
- – Helps extend oil change intervals
Formulated for Maximum Durability
All Hot Shot’s Secret products meet or exceed CK-4/API SN or Euro OEM standards and are:
- – Designed to reduce soot, deposits, and oxidation
- – Backed by real-world testing and wear data
- – Compatible with Hot Shot’s Secret TBN Booster and oil analysis program
Which 5W-40 Oil Should You Choose?
Use this table to match your engine and duty cycle.
| Green Diamond Fleet 5W-40 | Blue Diamond PAO 5W-40 | Gray Diamond 5W-40 |
| For fleets and severe duty applications | For maximum longevity and performance in heavy-duty diesel engines | For light-duty European vehicles |
| Best for upgrading older fleets to synthetic | Choose this if you want to push oil life to 100K miles | Designed to protect high-performance turbocharged gas and diesel engines |
| Provides reliable wear protection and emissions compliance | PAO base oil outperforms all conventional synthetics in oxidation, wear and heat resistance | Clean-burning mid-SAPS formula keeps DPFs and catalysts running clean |
Frequently Asked Questions About 5W-40 Oil
Find out more about Hot Shot’s Secret 5W-40 from these FAQs.
Can I use 5W-40 instead of 15W-40 in my diesel truck?
Yes, especially in colder climates. 5W-40 offers better cold starts while maintaining comparable hot-temperature protection to 15W-40.
Is 5W-40 good for extended oil change intervals?
Absolutely — when using Hot Shot’s Secret oils with oil analysis, intervals can extend up to 100,000 miles (especially with Blue Diamond).
What’s the difference between Group III, IV and V base oils?
- – Group III: Highly refined synthetic oils (used in Green Diamond and Gray Diamond)
- – Group IV: Pure PAO synthetics for maximum performance (Blue Diamond)
- – Group V: Specialized esters that enhance thermal stability and solvency (used alongside PAO in Blue Diamond)
Maximize Diesel Engine Performance With Hot Shot’s Secret
Backed by science, trusted by fleets and proven in extreme conditions — contact us to learn more about how our premium 5W-40 oil can help keep your vehicle or fleet running smoothly.
Shop our 5W-40 oil lineup today to experience superior protection, reduced maintenance and optimized engine life!