Dear Tom and Ray:
Is there any merit to the claim that nitrogen in gasoline has any benefit for cleaning the engine? What's the chemistry behind it? Or is this just the latest gasoline-additive scam? --David
Tom: Hmm. Maybe they're trying to get rid of all that excess nitrogen that they couldn't talk people into buying and using in their tires?
Ray: You're asking about Shell Oil Company's latest campaign, David, in which it claims that its gasoline is "nitrogen enhanced." And like most of the "enhancement" offers that come via email these days, David, this claim probably should be ignored.
Tom: Shell claims that its new nitrogen-enhanced gasoline keeps your engine cleaner.
Ray: Here's the story. Every gasoline is required to use a certain minimum amount of deposit-control additive -- which does help keep deposits from forming on your valves and other engine components. All of these additives contain small amounts of nitrogen.
Tom: But nitrogen is only one of several ingredients in these cleaning additives. So my guess is, Shell has increased the amount of cleaning additive in its gasoline, which has "enhanced" the nitrogen component.
Ray: And more cleaning additive is good. I mean, why not? It's such a small amount of nitrogen, compared with the volume of gasoline, that it doesn't affect the amount of nitrous oxides that come out of the tailpipe. And if your engine runs cleaner, that's all the better.
Tom: But what the claim "nitrogenenhanced" doesn't tell you is how much additive the gasoline had in the first place, and how much it has now. Maybe Shell used to add the absolute minimum necessary? Maybe it already was good, and got better? There's no way for us to know, as these are trade secrets. And by claiming its gasoline is enhanced, all we know is Shell is using more now than it was before.
Ray: Right. It would be like me and my brother claiming that our newspaper column is now "enhanced with right answers." It could mean that we really are trying harder and putting more time into answering each question. Or it could mean that we've enhanced the column to the point that we now get at least one answer right a year.
(Car Talk is a nationally syndicated column by automotive experts (and brothers) Tom and Ray Magliozzi. Write to them at the Car Talk Web site.)
2 Comments
By fuel guru on July 26, 2009 9:57 AM
Shell gasoline is certified as Top Tier gasoline, as are several other brands of gasoline. Top Tier gasoline is a cooperative effort between Honda, BMW, GM, Toyota, Audi, Volkswagen and gasoline suppliers, with the goal of keeping engines clean. In 1996 the US EPA mandated a minimum amount of deposit control additives in gasoline, and since then the amount of deposit control additives in gasoline dropped by 50%. Why did it drop? The oil companies and gasoline suppliers WERE PUTTING MORE ADDITIVES IN GASOLINE THAN THEY NEEDED TO!!!
Fuel suppliers could submit multiple gasoline samples for testing with decreasing doses of additives (which are added to gasoline in the parts per million range) and even though a supplier might have multiple failures of this test with low additive concentrations, all a supplier needs is one pass at a low dose rate, and their additive is certified at that low dose rate. This is known as EPA Lowest Additive Concentrate, or EPA LAC gasoline.
Auto manufactures saw the results of EPA LAC gasoline in their customer’s vehicles which degraded vehicle performance, resulting from deposits. The technical term for your engine getting gunked up with deposits is known as, among other things, Octane Requirement Increase. As you well know, clean fuel injectors produce a fine mist which maintains new vehicle performance. Clogged fuel injectors produce a spray with fuel droplets, which have a negative effect on emissions and vehicle performance. Further down in the engine, intake valves collect this gunk and further reduce engine performance. Dirty intake valves soak up fuel and create a lean burn situation, especially at start up. Intake valve deposits also hold more heat than clean intake valves, which tends to pre-heat the air/fuel mixture, which contributes to pre-ignition, lost performance and higher emissions. Gasoline deposits wreak the most havoc inside the combustion chamber. Deposits on the top of the piston increase cylinder compression ratio and temperature, this in turn raises the vehicle octane requirement - this condition is known as Octane Requirement Increase, or ORI. Almost all of the vehicles on the road in the US are designed to burn 87 octane regular grade gasoline. It has been estimated that if you have a new vehicle with an 87 octane requirement, in as little as the first 5,000 miles of driving with EPA LAC gasoline, because of engine deposits it can create, the actual octane requirement of the vehicle could have gone up by 5 octane numbers. This means that your vehicle now needs 93 octane gasoline to reach fuel equilibrium. Most drivers have no idea this is occurring because it is gradual process that happens over time, so the engine control system adjusts to this change in octane requirement by retarding performance so knocking does not occur during acceleration.
The insidious part of this story is that EPA LAC gasoline only has to keep fuel injectors and intake valves clean to a certain degree, and this gasoline has a stellar reputation for taking injector and intake valve deposits and washing them downstream into the combustion chamber where they cause the most engine damage and reduce performance the most, through ORI. Combustion chamber deposits are by far the hardest to clean. Part of the top Top Tier gasoline certification is your deposit control additive must not contribute to combustion chamber deposits, which is an advantage in maintaining new vehicle performance and emissions.
Here is an unbiased, educated industry insider opinion of Shell Oil, and their Nitrogen Enriched Gasoline. I must start by saying that Shell is recognized within the oil industry as a leader in research and development and bringing advanced fuels and lubricants to market. With that said, I would NEVER comment on what Shell Nitrogen Gasoline is. You guys are so right in saying that fuel additives are the most closely guarded secrets in the oil business. What I can say is, Shell gasoline IS a Top Tier gasoline, and Shell is only one of two major fuel suppliers that offer an even higher amount of gasoline detergency that will clean engines with deposits from cheaper gasolines, and help keep combustion chambers clean. I believe Shell claims double the amount of deposit control additives (required for EPA LAC gasoline) in their regular and mid grade octane gasoline, and five times the amount in their high octane gasoline. Since this type of “clean combustion chamber” gasoline is only available in the high octane grade, it can be referred to as the octane upgrade game - you have to buy the premium octane that 95% of the cars on the road don’t need in order to get a detergency level that will help keep your engine clean.
My work over the last several years with FuelGuru.com has been to bring awareness for the consumer to educate themselves on one of the biggest topics of discussion in America – gasoline. The FuelGuru mission has been to advocate for “clean gasoline detergency,” and develop programs where automobile service personnel are educated on the impact gasoline and lubricants have on vehicle systems. Service personnel play a vital role in the link between fuel and lubricant suppliers that want to bring better products to the market. The consumer needs verifiable results of the effectiveness of these products. That is where the educated service technician plays a vital role in linking top oil company decision makers with what the consumer needs and wants to make a difference in our global situation.
This issue of gasoline deposits has cost Americans BILLIONS in wasted gasoline. Keeping engines clean offers at least a 2% increase in fuel economy and reduced emissions. This 2% may not sound like much, but Americans consumed 132 billion gallons of gasoline last year, that is 2.64 billion gallons that could have been saved with cleaner gasoline. The average price for gasoline in the US for 2008 was $3.27 = $8,632,800,000.00. Over 8 billion dollars wasted last year because of dirty gasoline in the US! Amazingly enough, most Americans have never heard of this issue. It had been pretty much green washed over with sexy, fantasy cures that have left our nation’s fuel future broken down on the side of the road in the middle of no-where. By the way, burning less fuel is the best way to improve the environment and save money.
It is frustrating as an expert on transportation fuels to witness the mind numbing propaganda that has emerged over the last several years about how to improve our country’s fuel situation, and how almost ALL alternative fuel and vehicle programs that we have put enormous effort into have been on life support since the fall of oil prices. OUCH!!!
Jim Russo
Founder, FuelGuru.com
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