Choose a fuel additive by its purpose and compatible fuel.
Fuel additive is a general term for products added to fuels such as gasoline or diesel. Their intended purposes vary, including cleaning, corrosion prevention and maintaining fuel condition.
Adding one does not necessarily improve every car's fuel economy, and additives are not all the same. First check whether the product can be used in your vehicle. Then check whether its purpose matches what you want to improve or maintain.
This article builds on the distinction between fuel and oil products in the former LANDMASTER column, What Are Automotive Additives?, with updated product guidance and checks before use.
Fuel additives and oil additives go in different places.
| Category | Where it is used | What to check |
|---|---|---|
| Fuel additives | The gasoline, diesel or other fuel specified for the product | Compatible fuel and vehicle/equipment, dose and usage frequency |
| Engine oil additives | The engine oil specified for the product | Oil specification and viscosity, compatibility, application and dose |
Do not put a fuel additive into oil or an oil additive into fuel. Do not decide where to add a product from the phrase “for engines” alone; read its label and instructions.
See the roles and precautions of engine oil additives for more detail.
What is PEA? An ingredient used in fuel-cleaning additives.
PEA stands for polyetheramine. One example of a PEA-containing product is KURE Perfect Clean DX, which is described as cleaning deposits from injectors, intake valves and combustion chambers.
The same product also lists functions such as corrosion prevention and resistance to fuel oxidation. It is therefore inaccurate to assume that a product containing PEA only cleans. Check the functions and compatibility of the complete formulation, not just an ingredient name. KURE product information (Japanese)
For cleaning products, check the deposits they address, vehicle compatibility, dose and frequency. Cleaning alone will not resolve a vehicle problem caused by something else.
GERHON focuses on fuel and the combustion environment.
GERHON Fuel Conditioning, offered by NEXT SCIENCE, contains Asai organic germanium and is based on supporting equipment in maintaining its intended condition by conditioning the fuel.
It is an approach to everyday maintenance through fuel, not engine modification or rewriting control settings.
When comparing it with cleaning products, ask what you need and whether the product description and records address that need, rather than assuming a simple ranking. Products with different purposes do not need to be judged by one identical figure.
The earlier GERHON 3+ and the current range
The earlier GERHON 3+ is a product compatible with gasoline, diesel and kerosene. The current GERHON Fuel Conditioning range, by contrast, has separate gasoline, diesel and kerosene products.
The current range was developed by improving and building on earlier GERHON products. Do not apply the old “one product for three fuels” description to each of the current dedicated products. Choose the version matching your fuel.
Choose GERHON for your fuel
For gasoline
For considering condition maintenance in gasoline-powered cars, motorcycles and similar equipment.
View gasoline-product specifications, prices and instructions
For diesel
For diesel-powered vehicles, trucks, construction machinery, agricultural machinery and generators.
View diesel-product specifications, prices and instructions
For kerosene
For kerosene stoves, fan heaters and oil-fired boilers. Do not use it in kerosene boilers without a thermostat.
View kerosene-product specifications, prices and precautions
Also check the vehicle or equipment manufacturer's requirements. Ask before use if compatibility is unclear.
Check dose, timing and frequency together.
GERHON's specified dose
Each current GERHON product uses 0.5 mL per 1 L of its compatible fuel: 10 mL for 20 L.
| Compatible fuel quantity | GERHON quantity |
|---|---|
| 10 L | 5 mL |
| 20 L | 10 mL |
| 30 L | 15 mL |
| 40 L | 20 mL |
| 50 L | 25 mL |
This is GERHON's specified dose, not a universal dose for other brands. Follow the instructions for each product.
Do not assume that more is better.
Adding a quantity based on maximum tank capacity when little fuel is present changes the intended concentration. Check the amount of fuel actually being treated and use the specified dose.
The gasoline and diesel product descriptions allow addition before or after refueling. Check the label of the specific version for its method and precautions.
Usage frequency differs by product.
Distinguish products used at set intervals from those intended for continuous use at refueling. There is no universal rule that all fuel additives should be added every time, or only once every few thousand kilometers.
Read more about usage frequency and timing
Check before combining products.
Products that can be used individually have not necessarily been assessed in combination. Avoid mixing them on your own judgment or adding extra next time to make up for a missed dose. Ask each product's manufacturer before combining.
Keep ignition sources away during refueling and addition, and follow the vehicle, equipment and refueling-facility instructions. Stop and investigate if leakage or anything abnormal is noticed.
Precautions before using fuel additives
When evaluating effectiveness, read the test conditions too.
Numbers cannot be compared directly when vehicles, products, dates, concentrations or methods differ. Fuel economy, exhaust components, used-oil analysis and driver impressions are separate kinds of information.
GERHON's historical test and usage records are organized by fuel as technical records connected to the current products.
- Gasoline: 1985 10-mode tests and 1993 used-oil analysis
- Diesel: 1983 engine testing and a 1996 logistics field report
The published values were obtained using the products and conditions of their time. They do not guarantee the same percentage change with the current product or identical results in every vehicle. Results for different fuels are kept separate; a diesel field report is not presented as a gasoline result.
Servicing may be necessary before considering an additive.
If warning lights appear, power suddenly drops, vibration or noise becomes strong, or a fuel leak is suspected, investigate the cause before using an additive and waiting to see what happens.
Additives do not repair broken components. They do not replace scheduled inspections, specified oil changes or tire-pressure management.
For fuel kept in storage for a long time, check its condition first rather than assuming an additive can restore it to new fuel. Read about gasoline storage and deterioration
Frequently asked questions
Does every car need a fuel additive?
No universal need applies. Consider the vehicle's requirements, present condition and intended purpose.
Are PEA products or GERHON better?
That comparison alone is insufficient. Check each product's design objectives, vehicle and fuel compatibility, test records and usage conditions. Products centered on cleaning may also provide other functions.
Will GERHON always improve fuel economy?
The same change is not guaranteed under every condition. To evaluate fuel economy, keep refueling records using the same method before and after use, and note road conditions and maintenance changes.
Can the gasoline product be added to diesel?
The current range is fuel-specific. Choose the gasoline version for gasoline, diesel version for diesel and kerosene version for kerosene.
What if I am unsure which product to choose?
Tell us the vehicle or equipment name, year, fuel, any additives currently used and your objective. Confirm compatibility and instructions before choosing.
Conclusion: define the purpose, match the fuel and follow the dose.
These are the three basics of choosing a fuel additive. Look for explanations and records that match your use, rather than choosing solely by broad promotional claims.
Choose GERHON by fuel type / Ask about compatibility and use
Sources and editorial history
On September 7, 2026, the themes of the former LANDMASTER column, What Are Automotive Additives? (Japanese), were integrated into this article. Guidance on the three current GERHON products, usage conditions and technical records was updated. The distinction between fuel and oil products is retained, but the old article's blanket effectiveness claims and recommendations to combine products were not reproduced unchanged.
The example functions of a PEA-containing product are based on the KURE information linked above. GERHON applications and doses are based on its product pages; historical dates and evidence context are based on the fuel-specific records. Descriptions of other manufacturers' products do not directly establish GERHON's effectiveness.