By Jim Kerr
I’ve seen the ads on TV about Shell’s nitrogen-enhanced V-Power gasolines and always wondered if the claims of increased performance when using their fuels were true or just the creative wording of some advertising executive. After all, fuel is fuel and adding nitrogen to fuel wouldn’t seem to make much difference because air is already made up of about 76 per cent nitrogen. So what’s the story behind the Shell advertising claims? How do they add nitrogen to the fuel, what does it do, and does it really work? Recently, I spent some time with two Shell fuel specialists, Alex Drohomyrecky from Ontario and Bobby Bowden from Texas. They showed me some very interesting physical evidence and answered many questions on fuels and how they affect our vehicle engines.
All gasoline, regardless of supplier, is similar in its base form. Some gasolines contain ethanol – more on that later. All gasolines contain deposit control additives. There are standards set by the Environmental Protection Agency in the U.S. that specifies the minimum amount of deposit control additives in gasoline and Canada follows similar standards.
According to Drohomyrecky, it is estimated that about half of the gasoline sold in Canada contains near minimum allowable levels of deposit control additives but some gasolines contain more. This is where Shell claims their superiority. Their V-Power premium gasoline contains five times the minimum level of deposit control additives, and even their Shell Bronze grade fuel has much more than minimum standards.
You may have noticed that the same tanker truck companies fill the fuel tanks at many different service stations. That doesn’t mean the gasoline at each station is the same. When a truck pulls up to the refinery or bulk storage facility, the driver puts their “credit card” into the computer at the filling platform. This card tells the computer where the gas is to be delivered and what grade to deliver to the truck. The computer also selects the additive mix from their storage tanks and blends the additive with the gasoline as the truck is being filled. Then the truck delivers the fuel. Every truck load could contain different blends of fuel, based on what the company that is buying it wants. Shell doesn’t produce the additives but works closely with the chemical companies to design additives to work in the gasoline.
What do deposit control additives do for our vehicles? Deposits form on the back side of valves and in combustion chambers as the engine runs. The deposits can form in as little as 8000 kilometres. Deposits on the back side of valves can cause driveability hesitations and decrease fuel economy. Deposit control additives keep them from forming.
In 2005, Shell had four vehicles modified in Canada to show the differences fuels can make. Two complete fuel systems are installed on each vehicle, with separate tanks, fuel lines and separate fuel rails and injectors on the V6 engines. When the car is started, three of the cylinders operate on one fuel, while the other three operate on another fuel. After running the vehicles for a while, the engines were disassembled and the amount of intake valve deposits was measured. In a Montreal area tests, a competitor’s gasoline created 192.2 grams of deposits while the Shell Bronze fuel created only 35.5 grams. A second test with another competitive fuel showed 104.1 grams of deposits vs. 17.3 grams with the Shell Bronze.
Bobby Bowden of Shell showed me physical evidence of this on the Shell test vehicle. With the fuel injectors removed, we looked at the back side of the valves with a borescope. The back side of the three valves fuelled by Shell fuel showed no deposits, while the other three fuelled by a competitive fuel showed significant amounts of deposits.
Nitrogen in the additive package is part of Shell’s blend. The nitrogen is added at the molecular level to increase the solubility and stability of the other additives so they remain active during the combustion cycle. Most additives collapse under high heat and pressure, but the nitrogen creates a polar molecule (a molecule in which there is some separation of charge in the chemical bonds) that adheres to metal surfaces to prevent deposits forming and cleans existing deposits.
Chemical engineers might laugh at my description, but in simple terms, the nitrogen helps the other additives work.
As for ethanol added to gasoline, Drohomyrecky says ethanol produces deposits as well, so having deposit control additives is even more important. Not all fuels are the same, and Shell has proven it to me.