Frequently asked questions

Mobil Fuels FAQs

Find out more on commonly asked questions by selecting the relevant category.

Mogas FAQ

A detergent additive is present in Mobil petrol grades Special Unleaded 91, Special E10 94, Extra 95 and Supreme+ 98 and in Mobil Diesel grade Special Diesel at all participating Mobil branded sites & 7-Eleven stores. The additive is designed to improve engine performance by helping vehicle engines run more smoothly. It works to help remove harmful deposits from vital engine parts (fuel injectors and intake valves) that can build up over time. Whichever fuel you pump, the new Mobil fuels at participating Mobil branded sites & 7-Eleven stores help provide better fuel economy.

Over time deposits can form on intake valves and injectors that can reduce the efficiency of the fuel delivery into the combustion chamber and consequently the ability of the fuel charge to burn smoothly. Mobil’s detergent additives are added to our branded petrol and diesel grades, available at participating Mobil branded sites & 7 Eleven, in concentrations sufficient to help clean intake valves and port fuel injectors and keep them clean with continued use of the fuel.

Our new fuels help reduce and prevent deposits on intake valves and fuel injectors in order to help:

  • Improve engine responsiveness
  • Improve emissions and
  • Improve fuel economy

Special Unleaded/Special E10

Helps to improve:

  • Fuel economy
  • Emissions


Helps to improve:

  • Engine responsiveness
  • Fuel economy
  • Emissions


This premium grade petrol is engineered for top performance and helps to improve:

  • Engine responsiveness
  • Energy efficiency
  • Fuel economy
  • Emissions

Special Diesel

Helps to:

  • Improve fuel economy
  • Provide a cleaner, faster fill
  • Improve emissions

To read more on Special Diesel, please click here.

All above benefits are compared to unadditised fuel.

Mobil continually enhances its products to ensure they meet evolving engine technology needs. Our new fuels, now with detergent additives, are designed to keep engines clean and help clean up existing intake valve and fuel injector deposits. This performance is available across our entire fuel range at participating stores. We use higher levels of detergent in Supreme+ 98 for even greater performance.
The new additives will get to work from the first time they are introduced to your engine, but just how quickly an individual driver will notice the effect depends on a number of factors such as the age of the car, the condition of the engine, and how the vehicle is driven.

Octane FAQ

Mobil Fuel

  • Unleaded 91 is a 91 Research Octane Number (RON) rated fuel
  • Premium 95 is a 95 RON rated fuel
  • Premium 98 is a 98 RON rated fuel
  • E10 Unleaded is a blend of Unleaded 91 and Fuel Grade Ethanol complying with a minimum 91 RON rating. The fuel does get an octane boost from the Fuel Grade Ethanol and Mobil’s E10 is 94 RON

Mobil Additised Fuel

  • Special Unleaded 91 is a 91 Research Octane Number (RON) rated fuel
  • Special E10 Unleaded is a blend of Unleaded 91 and Fuel Grade Ethanol complying with a minimum 91 RON rating. The fuel does get an octane boost from the Fuel Grade Ethanol and Mobil’s E10 is 94 RON
  • Extra is a 95 RON rated fuel
  • Supreme+ is a 98 RON rated fuel

Colour of petrol grades is not regulated, however, the typical colours used in industry are:

  • Unleaded 91 & E10 Unleaded - Red or Orange
  • Premium 95 - Yellow
  • Premium 98 - Yellow

Occasionally, you may notice that the colour of the fuel is different to that which you are familiar with. This alone is not cause for concern as occasionally the fuel may have been left undyed or a higher octane grade downgraded.

No. The Australian standard for Premium Unleaded requires a Research Octane Number of Octane 95.0 minimum. The fuel suitable for your vehicle would be Premium 95 RON or for additional octane, Premium 98 RON.
Unleaded 91 and E10 94 do not meet the minimum RON requirement for Premium Unleaded Petrol. Mobil recommends that you follow the instruction of the vehicle's manufacture to ensure that you do not chance harming your engine or voiding your warranty.

Yes. In fact, petrol grades are subject to specified limits on many physical and chemical/compositional properties, in both Federal and State legislation. The main standard is the Federal Fuel Standard (Petrol) Determination 2001 available from the Federal government website.

Yes. Mobil branded petrol grades, available from participating Mobil branded sites & 7-Eleven stores, do contain a detergent additive package.

Yes. All petrol grades contain toluene in their total aromatics make-up. This is a normal chemical component of petrol produced through the refining process.

The fuel's octane rating is achieved from the inherent octane qualities of the blending streams. No additives are used to achieve the desired octane rating.

Ethanol FAQ

Ethanol is a non-fossil fuel that is produced from a variety of agricultural crops such as sugar cane and grains.

Unleaded E10 will contain up to 10% ethanol blended with unleaded petrol. The Australian government has limited the amount of ethanol in petrol to 10%, or ‘E10’.

Unleaded E10 fully complies with Australian Fuels Quality Standards and supports Mobil’s proud history of supplying high-quality fuels that you can trust.

Most cars built after 1986 are compatible with fuel blended with up to 10% ethanol whereas many pre-1986 vehicles are not. We recommend that you follow your vehicle manufacturer’s advice. The Federal Chamber of Automotive Industries (FCAI) website contains a comprehensive list of vehicles capable of operating on ethanol blends up to a maximum of 10% ethanol. If you are unsure about your particular model, you should consult your vehicle’s handbook or manufacturer.

The FCAI website includes a list of manufacturer contacts. If you own a pre-1986 vehicle and you currently use an antivalve seat recession additive with your petrol, we recommend that you continue to do so with Unleaded E10.
Yes. If you currently use an anti-valve seat recession additive with your petrol, we recommend that you continue to do so with Unleaded E10.
Ethanol is a high-quality, high-octane fuel component. The octane in Unleaded E10 is typically above 93 RON whereas regular unleaded petrol is 91 to 92 RON. Unleaded E10 also contains a corrosion inhibitor to protect the fuel system.
While ethanol contains less energy than normal petrol, any changes in the fuel economy of your vehicle by using Unleaded E10 should be small. There are many variables that can affect fuel economy including the season, weather, road condition, tyre pressure, the use of air conditioners, and whether or not the vehicle is properly tuned.
NO. Unleaded E10 is NOT suitable for any type of aircraft.
You should check with the equipment's manufacturer to see if ethanol-blended fuels are appropriate for use.

Many motorcycle manufacturers do not recommend using ethanol-blended petrol in motor cycles. Check your owner’s handbook or call your engine's manufacturer to see if ethanol blended fuels are appropriate for use. The Federal Chamber of Automotive Industries website, also contains a list of motorbikes capable of operating on ethanol blends up to a maximum of 10% ethanol. The FCAI website includes a list of manufacturer contacts.

You should check with the equipment’s manufacturer to see if ethanol-blended fuels are appropriate for use.
It is unlikely that one tank of Unleaded E10 will adversely affect the performance of your vehicle. We recommend that next time you fill your car you revert to using a non-ethanol blended fuel. Unleaded E10 is NOT recommended for all vehicles. If you have inadvertently filled your vehicle with Unleaded E10, you should contact your vehicle manufacturer or authorised representative.
Today's automotive fuel systems are generally closed systems and allow little moisture to enter. In fact, ethanol can help absorb small amounts of moisture in a fuel system and prevent fuel line blockage with ice in the winter.
Over time, some water accumulation is normal in vehicle fuel tanks. This occurs through condensation of moisture as temperatures cycle downward during the night.
In the unlikely event that the water level is too high, it can combine with the ethanol, separate and fall to the bottom of the vehicle's fuel tank. If this happens, the vehicle will not operate properly and the fuel will have to be removed (and disposed of properly) and replaced with new fuel. However, this situation is highly unlikely.

Diesel & Biodiesel FAQs

While diesel and petrol are both derived from oil, they work in different ways and are not interchangeable. Diesel fuel is designed to operate in a diesel engine, where it is injected into compressed, high-temperature air in the combustion chamber and ignites spontaneously. This differs from petrol, which is ignited in a gasoline engine by the spark plugs.
No. Suphur is a naturally occuring part of the crude oil from which diesel is obtained. In fact, the sulphur content of Automotive Diesel Fuel supplied at service stations in Australia is restricted to 10 milligrams per kilogram maximum, to achieve this ultra low content sulphur is actually taken out of the fuel during the refining process.
According to the Biofuels Association of Australia (BAA), biodiesel is a fuel product made from renewable plant or animal-based feedstock. It is normally used as a blend with petroleum diesel. The Australian Institute of Petroleum ( defines biodiesel (technically fatty acid methyl esters, or FAME) as esterified oil produced from a variety of sources such as canola oil, soybean oil, palm oil, tallow and even waste cooking oil.
Biodiesel blend, B”XX”, refers to the indicative volume percentage of biodiesel contained in a blend of straight biodiesel (B100) and diesel. For example, B5 is 4 - 5 vol % biodiesel and 95%+ (plus) mineral Automotive Diesel.
Biodiesel is produced from any triglyceride fat or oil such as soybean oil, tallow through a chemical process called trans esterification. Two products are generated from this process: fatty acid methyl esters (or FAME, the chemical name for biodiesel) and glycerin (a by-product used in soaps; the glycerin produced is essentially removed from the final biodiesel product).
The Australian Fuel Standard (Automotive Diesel) Determination 2001 allows for the inclusion of up to 5.0 % biodiesel by volume in all diesel fuel sold, provided that the biodiesel (B100) used in the blend meets the separate Fuel Standard (Biodiesel) Determination 2003. Mobil’s biodiesel blend stock (B100) purchase specification has additional requirements beyond those included in the Biodiesel Determination to further assure the quality of the product we provide to our customers.
No. The biodiesel blend stock (B100) specification contains a 10 ppm maximum sulphur limit, consistent with the Automotive Diesel sulphur specification. The B5 blend offered at Vopak Botany, Newcastle and Silverwater terminals will contain no more than 10 ppm sulphur.
The primary source is tallow based biodiesel. The biodiesel is sourced through domestic suppliers, which satisfy the NSW biofuels sustainability requirement. From time-to-time, however, producers may supply biodiesel from other feedstocks.

There are no legislative requirements to label diesel fuel containing 5% biodiesel or less. Refer to

Customers are advised to check their owner's manuals or contact the equipment manufacturers for specific fuel recommendations, including maximum recommended biodiesel concentrations for their specific vehicles or other diesel-powered equipment. Customers should avoid use of fuels with biodiesel concentrations higher than those recommended by the equipment manufacturers.
For B5: Yes. Once customers have confirmed their vehicle can use B5 they can switch back and forth between mineral diesel and B5 without issue. For blends with higher biodiesel contents (B6-B20): Customers should check their owner's manuals and contact their equipment manufacturers for specific fuel recommendations, including maximum recommended biodiesel concentrations for their specific vehicles/equipment and any required protocols for switching between biodiesel blends and mineral diesel fuel.
Yes, if you have been determined to be a volume seller for diesel under the Act. Our Biodiesel suppliers have confirmed that their product meets the Sustainability Criteria required under the Biodiesel Mandate legislation.
100% Biodiesel and biodiesel blends may not be compatible with some of the materials used in the construction of fuel storage and dispensing equipment. Biodiesel is known to be incompatible with certain elastomers and metals. We recommend that you contact the manufacturer of your fuel storage, handling and leak detection equipment to ensure that there are no compatibility or other issues.
Operators of storage facilities for any fuel always should be vigilant in their housekeeping practices to ensure that tanks are kept clean and dry. Housekeeping measures are particularly important when storing biodiesel blends because of their propensity to support microbiological growth and solvency. Biodiesel blends are more prone to support microbiological growth than petroleum diesel because biodiesel is a good food for microbes. In addition, biodiesel is a solvent that can release dirt and sediments in storage tanks systems. Both of these characteristics can cause contamination of the fuel and filter plugging. Microbiological growth can also promote corrosion of fuel system components. To prevent microbiological growth, it is important to ensure that tanks are free of water before they are filled with biodiesel products and to maintain careful water management practices. Where it is difficult to keep storage tanks dry the risk of microbial infection increases and it may become necessary to treat infected tanks with an appropriate biocide. The release of sediments and growth of microbes can cause clogging of fuel filters. Operators should be trained to look for signs of microbial contamination. Also, it may be necessary to change fuel filters more frequently, especially when first introducing biodiesel blends into a storage system.
Yes. Biodiesel should be used within three months or retested after three months to ensure the fuel continues to meet specifications. Directionally, biodiesel has a reduced shelf-life relative to petroleum diesel; thus, the greater percentage of biodiesel in the blended product, the shorter the product’s shelf-life. To help mitigate this impact, Mobil has a more stringent oxidation stability requirement for our biodiesel blend stock relative to the minimum Federal specification and we require that an oxidation stability additive be added to the biodiesel blend stock. Nevertheless, customers and end-users should be advised that all diesel fuels blended with biodiesel should be used within three months. This is particularly important if you know that the product may not otherwise be used by the customer or end-user for some time, e.g. if it has been purchased as back up fuel for emergency generators.
Yes, conditional upon a Section 13 Variation granted to Mobil under the Act. The Section 13 variation reduces the legislated Derived Cetane Number limit to 46 minimum and increases the upper Density limit to 860 kg/m³. However for B20 blended diesel to be considered compliant with the Act under the Section 13 variation it must continue to meet several conditions as instructed by the Federal Government. These conditions are elaborated on in the Questions and Answers below.
No. B20 blended diesel use is restricted by original equipment manufacturers. Please consult your Original Equipment Manufacturer(s) to confirm suitability/approval for use in your application before considering purchase of a B20 blended diesel.

No. It is a condition of Mobil’s Section 13 variation granted by the Federal Government that B20 must not be made available from publically accessible forecourts. This condition was also reinforced in the sales contract and a reminder notice of this restriction is printed on every Mobil delivery note. Failure to observe this condition of the Section 13 variation will render the fuel non-compliant with the Fuel Quality Standards Act 2000.

Other biodiesel information can be sourced from the following websites:

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*Mobil Special Diesel performance claims are based on internal and third-party customer testing, laboratory testing and/or literature support. Fuel economy testing was conducted using on-road trucks comparing performance to unadditised diesel. Actual benefits may vary depending on factors such as engine type, driving style, and fuel previously used.