Real-World Mileage Testing with a Volkswagen TDI

Customers sometimes ask whether a diesel fuel additive can improve fuel economy. The most honest answer is that results vary. Fuel quality, driving habits, vehicle condition, route, load, weather, and maintenance can all affect mileage.

One Real-World Example

This older customer-style comparison used a stock 2010 Volkswagen TDI driven on the same roads day after day. All products were used at the normal recommended dose.

Results reported in that test were:

No additive: 567 miles, 14.072 gallons, 40.29 mpg

Power Service Diesel Kleen: 604.3 miles, 14.369 gallons, 42.06 mpg

Opti-Lube XL Extreme Lubricant: 615.0 miles, 14.206 gallons, 43.29 mpg

Opti-Lube XPD: 635.7 miles, 14.245 gallons, 44.63 mpg

How to Read These Results

This type of test is useful as a real-world example, but it should not be treated as a guaranteed result for every vehicle. A diesel additive can help support lubricity, injector cleanliness, cetane, water separation, corrosion protection, and fuel quality, but fuel economy changes will vary from one engine and driving situation to another.

Best Takeaway

For most customers, the best reason to use a diesel fuel additive is long-term fuel system care and consistent fuel quality. If improved fuel economy follows, that is an added benefit.

Need help choosing? Start with Opti-Lube diesel fuel additives or review our FAQ for dosing, storage, and compatibility questions.

Which Opti-Lube Diesel Fuel Additive Should I Use?

Choosing the right diesel fuel additive depends on your main concern. Some customers want one all-around additive. Others are focused on maximum lubricity, stronger cetane, cold-weather protection, or a one-time fuel system cleaning treatment.

Quick Product Guide

XPD All-Season

XPD All-Season is our most popular diesel fuel additive because it covers the widest range of needs in one product. It supports lubricity, injector cleanliness, water separation, corrosion protection, fuel stability, cetane improvement, and cold-weather performance.

XL Extreme Lubricant

XL Extreme Lubricant is the best choice when maximum lubricity is the main goal. It is popular in warm climates, older diesel engines, equipment, and applications where fuel system wear protection is the top priority.

Summer+

Summer+ is a warm-weather formula focused on lubricity, cetane, detergency, and performance. It is a good option when anti-gel protection is not needed.

Boost!

Boost! is the best option when the main goal is cetane improvement. Higher cetane can help with cold starts, smoother combustion, reduced ignition delay, and overall drivability.

Winter

Winter is designed for stronger cold-weather anti-gel protection. It should be added before fuel reaches its cloud point or begins to gel.

Single Clean and Gel Melt

Single Clean is a stronger one-tank cleaning treatment for injector deposits, smoke, rough running, or fuel system cleanliness concerns. Gel Melt is an emergency product for diesel fuel that is already gelled.

Need help choosing? Start with Opti-Lube diesel fuel additives or review our FAQ for dosing, storage, and compatibility questions.

Why Is a Diesel Fuel Additive So Important?

Diesel fuel quality can vary by supplier, region, season, storage conditions, and fuel type. A good diesel fuel additive helps support fuel quality and can address several concerns that matter to modern and older diesel engines.

Lubricity

Lubricity is one of the most important reasons customers use diesel fuel additives. Fuel pumps and injectors rely on the fuel for lubrication. XL Extreme Lubricant is the best choice when maximum lubricity is the main goal, while XPD All-Season provides strong lubricity as part of a broader all-around formula.

Cetane

Cetane relates to how readily diesel fuel ignites during combustion. A higher cetane number can help with cold starts, smoother operation, reduced ignition delay, and drivability. Boost! is the best choice when maximum cetane improvement is the main goal.

Cold-Weather Performance

Cold temperatures can cause wax in diesel fuel to form crystals that restrict flow, especially at the filter. Winter is designed for severe cold-weather anti-gel protection, while XPD All-Season provides cold-weather support as part of an all-around additive.

Deposit Control

Modern diesel fuel systems operate at high pressures and have very small injector openings. Deposit control helps maintain spray pattern and fuel system cleanliness. Single Clean is a stronger cleaning treatment, while regular maintenance additives help keep the system clean over time.

Water Separation and Corrosion Protection

Water in diesel fuel can cause corrosion, filter plugging, microbial growth, and fuel system problems. Opti-Lube diesel additives are designed to support water separation so the fuel/water separator can do its job.

Need help choosing? Start with Opti-Lube diesel fuel additives or review our FAQ for dosing, storage, and compatibility questions.

Opti-Lube Ag Formula for Agricultural Diesel Equipment

Agricultural diesel equipment often has a different use pattern than daily-driven vehicles. Equipment may sit for long periods, run hard during certain seasons, and rely on stored fuel from bulk tanks.

Common Fuel Concerns in Agriculture

• Lubricity for pumps and injectors.
• Fuel stability during seasonal storage.
• Water contamination in tanks and equipment.
• Cold-weather operability when equipment is used in winter.
• Injector cleanliness and consistent performance under load.

Choosing an Additive

The best product depends on the application. XPD All-Season is a good all-around choice. XL Extreme Lubricant is best when maximum lubricity is the main goal. Preserve is a good fit for stored fuel, and Winter should be considered when severe cold-weather anti-gel protection is needed.

Need help choosing? Start with Opti-Lube diesel fuel additives or review our FAQ for dosing, storage, and compatibility questions.

What’s the Difference Between Opti-Lube Diesel Fuel Additives?

One of the most common questions we get is: what is the difference between your diesel fuel additives? The short answer is that each product is designed for a different need.

Quick Product Guide

XPD All-Season

XPD All-Season is our most popular diesel fuel additive because it covers the widest range of needs in one product, including lubricity, cleaning, water separation, corrosion protection, stability, cetane improvement, and cold-weather support.

XL Extreme Lubricant

XL Extreme Lubricant is the best choice when maximum lubricity is the main goal and anti-gel protection is not needed.

Summer+ and Boost!

Summer+ is a warm-weather formula with lubricity, cetane, detergency, and performance benefits. Boost! is the best choice when the main goal is maximum cetane improvement.

Winter, Single Clean, and Gel Melt

Winter is for stronger preventative cold-weather anti-gel protection. Single Clean is for stronger one-tank cleaning. Gel Melt is for emergency use when diesel fuel is already gelled.

Need help choosing? Start with Opti-Lube diesel fuel additives or review our FAQ for dosing, storage, and compatibility questions.

What Is Cavitation and Why Is It Bad for Injectors?

Cavitation happens when tiny vapor bubbles form and collapse in a liquid under certain pressure conditions. When those bubbles collapse near metal surfaces, they can create very small but powerful impacts.

Why It Matters

In diesel fuel systems, pressure changes, flow restrictions, and high operating pressures can create harsh conditions. Over time, poor fuel quality, inadequate lubricity, contamination, or water can contribute to wear concerns in pumps and injectors.

How Additives Help

A quality diesel fuel additive can support lubricity, water separation, corrosion protection, and fuel cleanliness. These benefits help create a better fuel environment for pumps and injectors, although additives do not replace proper filtration, maintenance, or repair.

Best Product Fit

XL Extreme Lubricant is the best choice when maximum lubricity is the main goal. XPD All-Season is a strong all-around choice when lubricity is one of several concerns.

Need help choosing? Start with Opti-Lube diesel fuel additives or review our FAQ for dosing, storage, and compatibility questions.

Diesel Fuel Lubricity Comparison: Why HFRR Testing Matters

Lubricity is one of the most important reasons diesel owners use a fuel additive. Diesel fuel is not only burned for power; it also helps lubricate pumps and injectors.

What Is HFRR?

HFRR stands for High Frequency Reciprocating Rig. It is a common lab test used to evaluate diesel fuel lubricity. The test produces a wear scar measurement, and in general, a lower wear scar number indicates better lubricity.

Why Lubricity Matters

Modern fuel systems operate at high pressures and tight tolerances. Better lubricity can help reduce wear in fuel pumps and injectors. This is especially important for customers focused on long-term fuel system protection.

Opti-Lube Product Fit

XL Extreme Lubricant is the best choice when maximum lubricity is the main goal. XPD All-Season also provides strong lubricity as part of a broader all-around diesel additive package.

A Note About Test Results

Lab tests are useful because they provide controlled comparisons, but real-world performance also depends on fuel quality, maintenance, operating conditions, filtration, and dosing.

Need help choosing? Start with Opti-Lube diesel fuel additives or review our FAQ for dosing, storage, and compatibility questions.