Petrol
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Reducing the maximum aromatics limit to 35%
We propose to reduce the maximum allowable aromatics limit to 35% for all petrol grades.
What are aromatics?
Petrol is a blend of components produced in refineries rather than a straight-run product distilled from crude oil, like jet fuel and diesel. Depending on the requirements of the final specification, different volumes of each component are used.
Aromatics are generated in the refining process to increase the petrol’s octane rating. Typically, higher-octane petrol will have a higher aromatic content. Octane enhancers are used in fuel to reduce engine knocking. Historically, lead was a petrol additive used to raise octane until it was removed due to the damage it did to people’s health (and along with other metallic additives is banned in most petrol, including New Zealand’s).
However, fuels with high aromatic levels can lead to onboard diagnostic failures, and potentially early failures and warranty issues for emissions critical hardware for newer vehicles that are designed to meet Euro 6. Further, the combustion of aromatics can create carcinogenic benzene in exhaust gases. Lowering aromatic levels reduces noxious emissions.
Current Regulations
The current New Zealand specification has a 45% maximum aromatic limit for fuel batches. This is high by international standards. Europe currently has a 35% aromatics limit and Australia will introduce a 35% limit for 95 petrol from December 2025. Even in New Zealand, aromatic levels for all grades of petrol that are imported fall below this 45% maximum limit on average.
The former Marsden Point Refinery produced a petrol that was much higher in aromatics than most imported petrol. Since the refinery’s closure, we have seen a large decrease in the aromatic content of our fuels. In 2019, the average aromatic content that was tested by MBIE was 35.5%. In 2023, this had dropped to an average of 26.8%.
However, while the pool average quality[2] of New Zealand petrol meets the limit for Euro 6d quality fuel (35%), premium grades of petrol tend to have higher than average aromatic levels. For instance, premium 98 fuel, which has the highest octane level available for retail sale, had an average aromatic level for 2022-23 of 34.8%.
Alternative octane enhancers, such as ethanol, would likely be needed to make higher octane grades, particularly 98 RON petrol.
What are the options?
The options for the maximum aromatic level are:
- Retain the maximum level of aromatics at 45% (ie retain the status quo).
- Reduce the pool average level of allowable aromatics to 35% and keep the maximum at 45%.
- Reduce the pool average level of allowable aromatics to 35% and reduce the maximum to 40%.
- Reduce the maximum allowable aromatics level to 35% for regular and 95 RON fuel but allow up to 40% on 98 RON fuel.
- Set a maximum 35% aromatic level on all fuels and leave the market to adjust.
Proposal and rationale
We propose to set a maximum aromatic limit of 35% from 1 December 2025 (option 5). It would allow us to keep pace with international vehicle emissions standards (such as Euro 6d), while its impact on supply and costs would be nil for regular petrol, minor (0.2 – 0.5 cents per litre) for 95 RON petrol, and manageable (about 3 cents per litre) for 98 RON petrol. While there might be supply constraints for premium fuel products with aromatics levels below 35%, these constraints are expected to be minor. Further, as other refineries in the region are upgraded (such as in Australia) there could be more supply options for Euro 6-compatible petrol by the end of 2025.
Questions for consultation
1. Should New Zealand reduce the allowable aromatic content of both regular 91, premium 95 and premium 98 petrol to 35%? If not, why not? What level do you consider it should be set at?
2. Should proposed changes come into effect from 1 December 2025? If not, why not?
3. If these proposed changes were implemented from 1 December 2025, would this delay the supply of Euro 6d petrol vehicles to New Zealand? Why?
4. Do you have any information on the likely cost impact of changing the maximum aromatic level for 95 and 98 RON petrol?
5. Besides ethanol, do you consider that there are any other octane enhancers that could be used to produce premium petrol with a low aromatic level, which should be allowed by the Regulations? If not, why not?
View the full list of questions for consultation
Assessment of options
The above options have been assessed below:
Table 1: Assessment of aromatics options
| Option 1: Status quo | Option 2: Reduce pool average to 35% and maximum stays at 45% | Option 3: Reduce pool average to 35% and maximum limit reduced to 40% | Option 4: 35% maximum on regular and 95 RON but allow up to 40% on 98 RON fuel | Option 5: Set a 35% maximum on all fuels from 1 December 2025 | |
|---|---|---|---|---|---|
| Noxious emission reduction | 0 There is no noxious emissions reduction benefit, since this option does not enable Euro 6 compatible fuel. |
0 There is no noxious emissions reduction benefit, since this option does not enable Euro 6 compatible fuel. |
0 This still does not achieve the ultimate outcome of fully Euro 6 compatible fuel and the associated noxious emission reduction benefits. |
+ This is still not in line with the ultimate direction of fuel specifications although it is better than the status quo from the perspective of noxious emission reduction, as this option ensures lower aromatics on two grades and at least one Euro 6 compliant grade (95 RON). |
++ This option would enable manufacturers to sell the latest engine technologies to the NZ market which will continue to improve fuel consumption and lower noxious emissions. |
| Consumer protection | - There is no guarantee that consumers who purchase Euro 6 vehicles will have access to compatible fuel. Vehicle damage may occur. |
- There is no guarantee that consumers who purchase Euro 6 vehicles will have access to compatible fuel. Vehicle damage may occur. |
- With this option, there is still no guarantee that consumers who purchase Euro 6 vehicles will have access to compatible fuel. Vehicle damage may occur. |
0 This option guarantees that 95 RON fuel becomes Euro 6 compliant, but not 98 RON fuel. Consumers who purchase Euro 6 vehicles which require 98 RON would not be protected. |
++ This option best aligns the specifications for the future. From a vehicle emissions hardware perspective, capping aromatics at 35% would make New Zealand fuel fully compatible with Euro 6 engine/emission designs and enable manufacturers to sell the latest engine technologies to the NZ market which will continue to improve fuel consumption and lower noxious emissions. |
| Economic cost | + No cost impacts are expected. |
+ No cost impacts are expected. Based on MBIE’s information on the pool average aromatic level, fuel suppliers can achieve this. |
+ It is likely that there would be a minimal impact on fuel supply and cost, as a 40% maximum aligns with the quality of standard Asian fuel imports. |
0 There would be minimal price impacts to 95 RON fuel (0.2 to 0.5 cent per litre), and no price impacts for 91 RON and 98 RON. |
- It is not expected that this option would affect the price of regular petrol. However, this option would have an impact on the cost of premium petrol. It would likely lead to a small increase in 95 RON cost (0.2 to 0.5 cents per litre (cpl)) and a larger increase in 98 RON (about 3 cpl) with possible difficulty in meeting supply for 98 RON fuel. About 25 per cent of petrol consumed in New Zealand is premium petrol. We do not have a breakdown between 95 RON and 98 RON, but 98 RON is likely to be needed by about 4 per cent of the fleet. |
| Government administration | 0 No change in government administrative burden is expected. |
0 No change in government administrative burden is expected. |
0 No change in government administrative burden is expected. |
0 No change in government administrative burden is expected. |
0 No change in government administrative burden is expected. |
| Summary | -1 | -1 | 0 | 1 | 3 |
Adding a silver strip corrosion test to detect active sulphur
What is active sulphur?
Sulphur is found naturally in crude oil. It is normally reduced to an acceptable level during the refining process and is subject to a maximum limit by the Regulations.
Active sulphur is sulphur that reacts with other chemicals. In an engine, active sulphur can react with the silver alloy used in fuel sender units inside the fuel tank of certain vehicles, resulting in the fuel gauge displaying erratic readings. Active sulphur can also react with the copper on fuel pump bearings, disrupting the smooth operation of fuel pumps and risking the vehicle stalling.
The Worldwide Fuel Charter, an international voluntary code for fuel quality, recommends that the silver strip corrosion test be applied to detect the presence of active sulphur compounds in petrol.
Current Regulations
The Regulations require a test for copper strip corrosion for petrol, but not a silver strip corrosion test. Both a copper and silver strip corrosion test can identify sulphur compounds, but it is only the silver strip corrosion test that can detect active sulphur, which can corrode or tarnish silver alloy fuel gauge in-tank sender units and silver-plated bearings in engines.
The current international standard methods for silver strip corrosion test are ASTM D7667 and ASTM D7671. In either method, a strip of silver is immersed in the test sample for a specified time and at a controlled temperature. It is then removed, assessed, and classified in one of five classes for colour and tarnish, from zero (no tarnish) to four (blackening).
There is a voluntary industrial specification for testing active sulphur in New Zealand, but compliance with it is not required under the Regulations. The fuel industry uses specific tests for Copper Corrosion (ASTM D130) and Silver Corrosion (ASTM D7667 or ASTM D7671) to identify if there are any reactive sulphur compounds in fuel, and prevent the release of problematic batches (where reactive sulphur compound is present in significant enough amounts to corrode test strips).
Proposal and rationale
We propose to add the silver strip corrosion test to Schedule 1 of the Regulations, with Class One standard (slight tarnish) being the limit, and ASTM D7667 or ASTM D7671 being the test method.
We prefer this option to the status quo because it formalises the need for a silver strip corrosion test. This would improve protection for consumers by minimising the risk of damage for fuel system parts, while the cost of a silver strip corrosion test would be minimal. Furthermore, introducing a silver strip corrosion test brings our fuel regulations more into line with international standards like the WWFC (Worldwide Fuel Charter).
Questions for consultation
6. Do you agree that we should add a silver strip corrosion test to the Regulations, Schedule 1, using either ASTM D7667 or ASTM D7671?
7. Do you have a preference on whether to use ASTM D7667 or ASTM D7671, or both?
Relaxing the specification to allow petrol with the 10ppm sulphur requirement to be used as a denaturant
What is denatured ethanol?
Ethanol is denatured (made unfit for human consumption) by blending it with another product or chemical. This is usually done before importation to avoid paying additional excise duty on alcohol.
Current regulations
The current regulations in New Zealand state that ethanol needs to be denatured with unleaded petrol. When unleaded petrol is used as a denaturant, it must comply with the regulations for retail sale (Regulation 8(3)(b)) and non-retail sale (Regulation 14(3)(a)) of petrol/ethanol blends.
Schedule 4 of the Regulations requires that:
- the denaturant must be 1-1.5% of the volume; and
- the unleaded petrol used as the denaturant must have 10 ppm (parts per million) or less of sulphur.
If unleaded petrol is used to denature ethanol before ethanol is imported, it is possible that the ethanol will not comply with New Zealand regulations requiring the petrol to have 10ppm, or less, of sulphur.
This will be particularly true of ethanol that could be imported from Australia. Australia’s maximum allowable level for sulphur in unleaded petrol is between 100 and 150 ppm, although legislation has been introduced that would reduce this level to 10ppm in 2025. In some instances, fuel from some Asian refineries can have sulphur of up to 500 ppm.
In effect, this regulation requires fuel companies to import undenatured ethanol and denature it in New Zealand to meet the requirement that the denaturant is petrol with 10ppm or less of sulphur.
Proposal and rationale
MBIE proposes to relax the New Zealand standard to allow denaturants that have more than 10ppm sulphur, provided the denaturant is petrol and the final denatured ethanol has less than 10ppm sulphur.
Questions for consultation
8. Do you agree that the maximum allowable sulphur requirement for ethanol denaturants should be relaxed, so long as the final denatured ethanol is less than 10ppm sulphur? If not, why not?
9. If the requirement is relaxed, should there still be a maximum allowable level of sulphur for denaturants? If so, what should that level be? If not, why not?
Introducing a density specification
What is fuel density?
Fuel density is the mass of fuel per unit volume. Density is determined by both the quality of crude oil used to produce the fuel and the refining process.
Current Regulations
The New Zealand specification does not currently have a density specification for petrol.
Many countries’ specifications have density ranges including the detailed EN228 (Euro 6) standards (eg BS EN228) where the density range allowed is 720-775 kg/m3. This is the same range as that recommended by the WWFC category 5 grade and Platts and Argus use a minimum specification of 720 kg/m3 for their petrol specification.[3]
If the density of petrol is below 720 kg/m3, then it is likely to mean the volumetric energy content is lower than expected, increasing fuel consumption and costs to the consumer. While infrequent, MBIE testing shows that petrol with a density below 720 kg/m3 does occur.
Proposal and rationale
The preferred option is to introduce a density range for petrol of 720–775 kg/m3. This would bring our specification into line with Euro 6 Standards. We understand this range is already in line with import standards set by the fuel industry and as such we do not expect the introduction of a fuel density range to have an impact on fuel security and price.
Questions for consultation
10. Should we introduce a petrol density range to the specifications? If not, why not?
11. If a range is introduced, should the density range be 720-775 kg/m3. If not, why not?
Miscellaneous technical amendments for petrol and ethanol specifications
We also propose several technical amendments. We do not anticipate that these technical amendments will have any impact on fuel prices or emissions.
Table 2: Miscellaneous technical amendments for petrol and ethanol specifications
| Proposed change | Reason |
|---|---|
| Revising the upper boiling point limit for petrol to 210°C in the definition of ‘petrol’ in Regulation 5. | For consistency with the specification for petrol in Schedule 1 of the Regulations. |
| Correcting the test standard for silver strip corrosion test in fuel ethanol — Schedule 1A should refer to ASTM D7667 and D7671 (the test standard for silver strip corrosion) rather than ASTM D130 (the test standard for copper strip corrosion). Note that this proposal refers to the existing silver strip corrosion test for fuel ethanol (Schedule 1A). It is different from the above proposal to add a silver strip corrosion test requirement for petrol (Schedule 1). |
This corrects a technical error and will help avoid issues with corrosive compounds in fuel damaging engine components. |
| Changing the ethanol content range in fuel ethanol by lowering the range from the range of 70 – 85% to a range of 51 – 83% as in ASTM D5798. | ASTM D5798 is the latest international standard for petrol-ethanol blends. Alignment with this standard would ensure proper vehicle starting, operation, and safety in varying temperature conditions. |
Questions for consultation
12. Do you support these technical amendments for petrol and ethanol specifications? Are there any that you disagree with? Why?
[3] Platts and Argus are two separate price reporting agencies that publish market prices that are used by the fuel industry to price their crude oil and products. They both report on the Asian product market and for each product quote there is a published specification that reflects the quote they are reporting on (generally a reflection of the most commonly traded specification).