Questions and Answers

Company Position

What is ExxonMobil's position on the 50 ppm sulfur diesel?

ExxonMobil fully supports the Singapore government's air quality improvement programme.

This is reflected in our active involvement in the 50 ppm sulfur diesel launch. From 1 December 2005, 50 ppm Synergy Diesel will be available at all Esso and Mobil service stations (except Esso Lorong Chuan and Mobil Bukit Timah).

Product Availability and Pricing

When will 50 ppm sulfur diesel be available at Esso and Mobil Service Stations?

50 ppm sulfur diesel will be made available at all Esso and Mobil service stations (except Esso Lorong Chuan and Mobil Bukit Timah) from 1 December 2005 in line with the mandated date set by the Ministry of the Environment and Water Resources.

We have Euro IV taxis. Can we fill up at Esso and Mobil service stations?

Euro IV taxis are designed to run on 50 ppm sulfur diesel. As 50ppm sulfur diesel will only be available at Esso and Mobil service station (except Esso Lorong Chuan and Mobil Bukit Timah) from 1 December 2005, Euro IV taxis will not be able to fill up at Esso and Mobil stations until 1 December 2005.

How do you determine the pump price of 50 ppm Sulfur Diesel?

Diesel pump prices are affected by a basket of factors. These include price of crude oil, wholesale product cost, storage, distribution and marketing costs, taxes, duties, currency exchange rates and market competition.

It will be more costly for ExxonMobil to manufacture and supply 50 ppm sulfur diesel compared with current diesel specifications. It costs more to remove the additional sulfur from diesel during the refining process.

This additional cost will therefore be taken into account - along with the other factors mentioned above - in determining our diesel pump prices when we introduce 50 ppm sulfur diesel.

Product Information

What is sulfur and why is it present in diesel?

Sulfur is an element. It is found naturally in crude oil. During the refining process, sulfur is removed to meet product specifications.

How does sulfur get reduced in the 50ppm case?

The sulfur in the diesel is reduced in the refinery process called “sweetening”. The most common method is to use hydrogen gas to convert the sulfur into H2S (hydrogen sulfide) in a process referred to as hydrofining. H2S is removed from the diesel for further processing.

What happens to the sulfur in the engine?

During combustion, sulfur compound in the fuel burns to form acidic by-products (such as sulfur dioxide, sulfur tri-oxide), and also sulfates, in the exhaust.

What are the characteristics of 50 ppm Synergy Diesel?

Synergy Diesel is 50 ppm sulfur diesel with multi-functional detergent additives.

This 50 ppm sulfur diesel contains a very low content of sulfur at 50 weight ppm (parts per million) - that is 90 % less than before. It improves vehicle exhaust emission. Currently, the maximum sulfur content allowed in diesel in Singapore is 500 ppm.

The detergent additives help to keep diesel engine fuel system clean, thus resulting in better combustion and emission improvement. Additionally, the lubricity component of additives also works to maintain anti-wear performance of fuel.

What is the difference between ULSD or 50ppm sulfur diesel and Euro IV diesel?

ULSD, or 50 ppm sulfur diesel, and Euro IV diesel basically refer to diesel fuel with sulfur content up to a maximum of 50 ppm (or 0.005 wt%).  There are other slight differences in the base diesel fuel which varies according to country regulations.

What is Euro IV diesel?

Euro IV refers to the product specification (ISO EN 590) set by European Committee for Standardization for compliance within the European Union.

Is Singapore the first/only country in Asia to use 50 ppm sulfur diesel?

No, Hong Kong was the first country in Asia to launch 50 ppm sulfur in 2001, followed by Japan in 2003. Australia and New Zealand will be launching 50 ppm sulfur diesel in January 2006.

What is the difference between 50ppm sulfur diesel in Singapore and ULSD in other countries (eg. Hong Kong, Australia) ?

The sulfur content of 50 ppm sulfur diesel in Singapore and other countries (e.g. Hong Kong, Japan, Australia and New Zealand) are the same (i.e. maximum 50 ppm). The quality of the base diesel fuel may differ from country to country due to local government regulations. 

Can 50ppm sulfur diesel be used in all diesel vehicles (eg. Euro II, Euro III)?

Yes, 50 ppm sulfur diesel is suitable for all diesel vehicles (including existing Euro II and Euro III diesel vehicles). As the 50 ppm sulfur diesel contains 90% less sulfur, this leads to lower sulfur dioxide exhaust emissions from diesel powered vehicles and hence, lower air pollution.

Is the colour of 50ppm sulfur diesel different from 500 ppm sulfur diesel?

No, there will be no change in the colour of diesel.

Is the quality of 50 ppm sulfur diesel as good as the current diesel?

The 50 ppm sulfur diesel is as good as the current diesel except the sulfur content is considerably lower. 

Will 50 ppm sulfur diesel affect engine performance?

No, we do not expect any adverse impact at all except possibly older vehicles manufactured before 1995.

How does 50 ppm sulfur diesel affect emission?

The introduction of 50 ppm sulfur diesel enables sulfur sensitive exhaust after-treatment (i.e. particulate traps) to be used which reduces particulates emission from vehicles. The reduced sulfur also improves the odour of diesel exhaust gas.

To what extent will 50 ppm sulfur diesel help to improve air quality?

As the Ministry of the Environment and Water Resources has clearly stated, 50 ppm sulfur diesel plays a key role in reducing the level of particulates, which is a key pollutant here in Singapore. But 50 ppm sulfur diesel alone is not adequate. We also suggest that other complementary measures be taken:

•   good driving habits

•   install particulate traps

•   regular vehicle repair and maintenance