JEDDAH, 3 January 2007 — Adib Al-Zaban, a Saudi car owner, has a gripe with local gas stations.

“My car, according to specifications of Saudi Aramco, requires Premium 95 but none of the fuel stations I visited today displayed signs that said my type of car needed Premium 95, and the use of the other grade would damage its engine,” said Al-Zaban who would like to see Saudi Aramco blacklist stations that do not follow the instructions with regard to the supply of the new gasoline.

Salim Abdul Salam, another Jeddah car owner, has a similar complaint. Contrary to Aramco recommendation that he use its new Premium-91 fuel, the gas station filled his tank with Premium-95. He said he believes running “95” would damage his engine.

But unless Abdul Salam just brought his car into Saudi Arabia, he’s been using 95-octane fuel all along. And Al-Zaban’s engine is fine running both types of fuel.

These misconceptions have emerged as Saudi Aramco has begun offering two grades of Premium fuel, 91 and 95, after a four-month massive promotion campaign.

Vehicle owners like Al-Zaban and Abdul Salam are confused about what grade suits their cars. They complain that the fuel stations do not display any stickers explaining the specifications of the new grade of gas to help them choose the right fuel, according to local Arabic newspaper Al-Madinah.

A majority of cars in Saudi Arabia can use Premium 91 and gain no increase in performance by using a 95-octane gasoline, according to an earlier statement of the Saudi Aramco. Premium 91 fuel costs about 15 halalas less per liter. Offering this lower price point at the pump was the primary reason for Saudi Aramco’s decision.

The company announced that the fuel stations would display notices showing the specifications and types of the vehicles that can use the newly marketed grade.

Abdul Salam may be wrong in thinking the wrong grade will damage his car’s engine, but he might have a point that gas stations and Aramco may not be doing enough to assure customers. And this misconception may be causing people to unnecessarily pay the 15 halalas per liter extra for the more expensive grade.

“The lack of cooperation by the station management to display the difference between the two varieties denies the public their opportunity to benefit from the reduced price,” he said.

Mazin Al-Fara, a Jeddah car owner that uses a company vehicle, said that he has noticed that most gas stations are still not offering both grades of fuel.

Meanwhile, customers — wary that their cars may be damaged — wonder what to do when they go to the pump. “If my car requires the costlier fuel I will get rid of it and buy another that uses Premium 91,” said Holail Al-Bugami, a Taif cab driver.

‘91’ or ‘95’ — What’s the Difference?

The numbers that denote Aramco’s new two-grade system indicate the respective fuel’s octane rating, an international standard that determines a fuel’s so-called auto-ignition resistance.

The lower the octane, the less likely the fuel will ignite prematurely in an engine due to the pressure of the power stroke. Some fuels will ignite due to the power stroke of the engine rather than with the timing of the engine’s spark plugs. Problems with pre-ignition causes some cars to “knock” at acceleration, when the pre-ignition of the fuel followed by the spark causes the combustion to stop prematurely, reducing a vehicle’s performance that can cause a “knocking” sound. The lower the octane rating, the more likely it is for fuel to ignite due to extreme pressure rather than a spark.

A common misconception is that higher-octane fuels burn better. Lower octane fuels are more likely to ignite under pressure rather than by sparks. Higher octane ratings increase performance in high-performance engines that are designed with higher compression of the air-fuel mixture inside the engines’ cylinders. In other words, most car owners will be fine running Premium 91 fuel. Saudi Aramco says 85 percent of vehicles in the Kingdom will not benefit from using higher-grade fuel.

“Using Premium 95 for these vehicles is a waste of money,” said Faisal Al-Moaiqel, director of local sales and technical support at Saudi Aramco.

Using the “wrong” grade of fuel will not damage a vehicle’s engine, but can hinder optimal performance in high-performance engines. Car manuals in newer luxury models often recommend using higher octane ratings.