When you’re hauling heavy loads day after day, your Western Star 5700XE needs an engine that works as hard as you do. The right setup can keep you on the road longer and out of the repair shop. But choose poorly, and you’re looking at rising fuel bills and costly downtime. This post helps you figure out what matters most, from performance to oil type, so you’re confident your truck’s engine can handle the long haul without letting you down.
Standard Option: Detroit DD15 Engine
The Detroit DD15 is the go-to engine for the Western Star 5700XE. Known for balancing power and efficiency, it’s built to handle demanding hauls while keeping your fuel bill under control. With a 14.8-liter displacement, horsepower that ranges from 455-505, and torque of 1550-1750 lb-ft, it’s a tough yet efficient choice.
What sets it apart is its downsped design, which means it gets the most out of every drop of fuel. This not only cuts costs but also reduces wear and tear. If you’re all about reliable performance and solid fuel savings, the DD15 checks the boxes.
Exploring Other Engines: Detroit DD13 and DD16
While the DD15 is standard, you’ve got options, depending on your needs. The Detroit DD13 is a smaller, lightweight engine with a 12.8-liter displacement. Despite its size, it delivers horsepower between 370-525 and torque ranging from 1250-1850 lb-ft. It’s ideal for jobs where weight savings and fuel efficiency are big priorities.
Need more muscle? Enter the Detroit DD16. With a 15.6-liter displacement, up to 600 horsepower, and massive torque of 1653-2050 lb-ft, this engine handles heavy loads like a champ. Sure, it burns more fuel, but if your hauls demand serious power, it’s worth it.
Synthetic vs. Conventional Oil: What’s Right for Your Engine?
Let’s be real—your engine oil plays a huge role in keeping your truck reliable. But not all oils are created equal. Understanding the difference between synthetic and conventional oil helps you make a smarter choice.
Synthetic motor oil is engineered for consistent and pure molecules without contaminants. This ensures reduced friction, better fuel economy, and stronger protection, especially in extreme hot or cold temperatures. Simply put, it outlasts and outperforms conventional options. Conventional oil, on the other hand, is derived from crude oil and comes with impurities like sulfur and metals. These impurities can mess with performance and cause wear over time. If you’re serious about protecting your engine, synthetic oil is where it’s at.

Recommended Oils for the Western Star 5700XE
When it comes to finding the best engine oil for your Western Star 5700XE, a couple of standout options make the list:
- Mobil Delvac 1300 Super 10W-30 Synthetic Blend Diesel Engine Oil: A solid middle ground, this oil delivers reliable performance and protection without breaking the bank. It’s great for everyday hauls and gives you decent fuel savings.
- AMSOIL Signature Series 10W-30 100% Synthetic Max-Duty Diesel Oil: If you’re looking for top-tier performance, this oil is a game-changer. It excels at reducing wear, boosting power, and extending oil change intervals. That means fewer visits to the shop and more time on the road.
Using high-quality oil like these keeps your engine running cleaner, longer, and more efficiently. Plus, both options meet the rigorous API CK-4 standards, which means they’re built to handle the stress of modern diesel engines.
Factors to Consider When Choosing Your Engine
Picking the right engine isn’t just about horsepower numbers. Here’s what else you’ll want to look at:
1. Fuel Efficiency
Don’t underestimate the cost of fuel. A more efficient engine, like the DD15, saves you thousands over the long haul. Look for engines with smart design features like turbocharging and downspeeding to maximize MPG.
2. Maintenance Needs
Can you easily find parts and get service for your chosen engine? Simpler maintenance means less downtime and fewer surprise expenses. Engines like those in the Detroit family are backed by a huge service network, so help is never far away.
3. Compatibility
Not every engine fits perfectly with the 5700XE’s specs. Make sure any alternative option is fully compatible with the truck and won’t cause unnecessary wear on other parts.
4. Performance for Your Hauls
Are you hauling lightweight or heavyweight loads? For heavier towing, prioritize high torque (like what the DD16 offers.) For lighter jobs, an efficient engine like the DD13 might be the better choice.
Keeping Costs Down and Reliability High
Whatever engine you go with, pairing it with the right products will stretch its performance even further:
- AMSOIL Diesel Injector Clean + Cetane Boost: This provides smoother starts, cleaner injectors, and up to 8% better fuel economy. It tackles tough jobs your engine faces daily, leaving less smoke and better power behind.
- AMSOIL NLGI #2 100% Synthetic Polymeric Grease: Perfect for truck and chassis maintenance. It reduces wear, eliminates frequent greasing, and saves money long-term.
- AMSOIL 80W-140 Long Life Gear Lube: Protects against heavy-load stress on your truck’s components, extending the life of your gears.
Get an in-depth look at the Western Star 5700XE’s standout features here on CCJ Digital.

Final Thoughts
Your Western Star 5700XE is more than just a truck; it’s an investment, and the engine is at the heart of it. Choosing the right one affects every mile you drive, every gallon of fuel you buy, and every service stop along the way.
Pair that engine with high-grade oils, synthetic lubricants, and targeted maintenance products to lower downtime and save money on fuel and repairs. Finding the right fit—whether it’s the DD15, DD13, or DD16—along with the best engine oil for Western Star 5700XE will keep your truck ready to handle whatever the road throws at you. For more details on high-performance motor oils, explore: Mobil here and AMSOIL Signature Series here.