If you own a Freightliner 108SD, you’ve probably heard a mix of opinions about synthetic oil. Does it cause leaks? Is it too expensive? Let’s set the record straight. This guide clears up some common misunderstandings and gives you the facts about synthetic oil, the Freightliner 108SD oil type, and how choosing the right oil can benefit your truck for the long haul.
The Truth About Synthetic Oil Additives
One of the biggest myths floating around is that synthetic oil causes your engine to leak. That’s not true. This misconception often comes from a misunderstanding of the additives used in synthetic motor oil.
Additives like detergents, anti-wear agents, and dispersants are designed to improve oil performance and keep your engine running smoothly. They help clean out sludge, stop deposits from forming, and minimize wear. The additives in synthetic oils don’t harm your engine; in fact, they strengthen seals and gaskets, reducing the risks of leaks.
What Does the Evidence Say?
Research consistently shows that synthetic oil doesn’t lead to leaks in properly maintained engines. Modern synthetic oils, like Delo 400 XLE SB SAE 15W-40 Synthetic Blend or AMSOIL Signature Series 15W-40 100% Synthetic Max-Duty Diesel Oil, are packed with advanced additives to protect and enhance engine components. Freightliner 108SD engines, built for toughness, can absolutely handle synthetic oils and thrive with the added benefits they bring.
Synthetic Oil vs. Conventional Oil: What You Should Know
Here’s the reality: synthetic motor oil is engineered from scratch. This means the molecules are consistent, pure, and free of contaminants like sulfur and metals. These impurities, found in conventional oil (refined from crude,) lead to inconsistent performance and reduced effectiveness.
The precision design of synthetic oil reduces friction, protects your engine better in extreme conditions, and even enhances fuel mileage. Conventional oil, while cheaper upfront, can’t match these performance gains. If you care about durability and efficiency, synthetic oil is hard to beat.

Long-Term Savings: Does Synthetic Oil Really Pay Off?
Some truck owners think synthetic oil costs too much, but here’s the real story. Over time, synthetic oil actually saves you money. Let’s break it down:
Fewer Oil Changes
Synthetic oil lasts longer than conventional oil. That means extended intervals between oil changes. With Freightliner 108SD engines, fewer oil changes can save you both time and money. Less downtime and fewer maintenance stops? Sounds like a win.
Reduced Wear and Tear
Synthetic oil provides a superior lubrication barrier. It reduces engine friction, cuts down on wear, and protects key parts like bearings and pistons. Over the years, this extra protection translates to lower repair costs and a longer engine life.
Better Fuel Efficiency
Freightliner 108SD trucks aren’t fuel sippers—but synthetic oil can help reduce fuel consumption. By minimizing friction, synthetic oil lets your engine run more efficiently, potentially saving you money at the pump. Combine that with reduced maintenance costs, and switching to synthetic oil starts to look like an investment rather than an expense.
Is Synthetic Oil Safe for Engine Seals?
Another myth that needs busting is the idea that synthetic oil damages engine seals. This outdated belief comes from the early days of synthetic oil tech. Fortunately, times have changed.
Modern synthetic oils are specially formulated to condition seals and prevent leaks. In fact, these oils actually help preserve the integrity of seals better than conventional oils. Freightliner 108SD engines, with their advanced designs, are fully compatible with today’s synthetic oils, making them a worry-free option.
Meeting Freightliner 108SD Oil Type Standards
When choosing oil for your Freightliner 108SD, look for products that meet or exceed the API CK-4 standards. Recommended choices like Delo 400 XLE SB SAE 15W-40 or AMSOIL Signature Series 15W-40 100% Synthetic Max-Duty Diesel Oil offer excellent protection, boost performance, and keep your engine running at its best.
- Delo 400 XLE SB SAE 15W-40: A synthetic blend that balances affordability with reliability. It’s ideal for operators who want solid performance without breaking the bank.
- AMSOIL Signature Series 15W-40: A premium, full synthetic option built for maximum protection. Great for heavy-duty engines that endure tough conditions.
Both of these options work perfectly for the Freightliner 108SD oil type. They provide exceptional wear protection, reduce carbon buildup, and maintain optimal engine performance.
Learn more about driving and maintaining Freightliner SD models here on Overdrive Online.

Wrapping It Up
There’s no need to get tripped up by outdated myths about synthetic oil. Between its long-term cost savings, enhanced protection, and compatibility with modern engines like the Freightliner 108SD, synthetic oil remains a smart choice for truck owners.
Don’t skimp on engine care. By sticking to high-quality synthetic oils like AMSOIL Signature Series or Delo 400 XLE SB, you’re giving your Freightliner 108SD the performance boost it needs to keep hauling tough loads with ease. Choosing the best engine oil for Freightliner 108SD oil type isn’t complicated—just make an informed decision and keep your truck in top shape. With synthetic oil, you’re not just maintaining your engine; you’re investing in its future. For more details on high-performance motor oils, explore: Chevron here and AMSOIL Signature Series here.