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.

Q&A: Can I Mix Multiple Opti-Lube Diesel Additives?

In short: yes, Opti-Lube diesel additives can generally be mixed. The main thing to remember is that each product is designed for a purpose, so mixing products is not always necessary.

Common Combinations

XL Extreme Lubricant and Boost! can make sense when a customer wants strong lubricity and a stronger cetane increase. XPD All-Season and Winter can also be used together when a customer wants XPD’s year-round benefits plus stronger cold-weather anti-gel protection.

When Mixing May Not Be Needed

Mixing XL and XPD All-Season is usually not necessary because both provide strong lubricity benefits. Summer+ may also provide the balance some customers are trying to get by mixing XL and Boost!.

Avoid Overdoing It

Using a little more than the recommended amount is usually not a concern, but significantly overdosing generally does not provide extra benefit and may not be cost-effective. Follow the directions on the bottle or product page for best results.

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

Tired of Measuring Diesel Additive for Every Tank?

Measuring diesel additive every time you fill up does not have to be complicated. The key is to know your tank size, understand the treatment rate, and use a container or dosing method that makes the amount easy to repeat.

Use the Right Treatment Rate

Treatment rates vary by product, so follow the directions on the bottle or product page. For example, XPD All-Season is commonly used at 1/4 oz per gallon of diesel fuel.

Make Dosing Easier

• Keep a dedicated measuring bottle in the vehicle.
• Pre-measure common amounts for your usual fill-up size.
• Add the product before or during fueling when possible.
• Use the same routine each time to avoid underdosing or overdosing.

What If You Add a Little Too Much?

A small amount over the recommended dose is usually not a concern. However, significantly overdosing generally does not provide extra benefit and is usually not cost-effective.

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.

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.