A building at the Shell Technology Center - Houston

Two of the most important additions to a car are also two of the most commonly ignored: gasoline and tires. Companies pour staggering amounts of money, energy and resources into designing, engineering and gaining percentile improvements in automobiles, and what they get in return from consumers is a staggering amount of "Which one is cheapest?"

So when Shell invited us to its Technology Center near Houston, TX for a closer look at its V-Power premium gasoline, we went for the chance to see the massive amounts of engineering and science that Shell (like other oil companies) puts into formulating its trademark gas – the same engineering and science that almost no one cares about.

It wasn't the trip we expected to take, nor is this the article we expected to write.

Then it came time to commit our findings to the Internet page. That's when we discovered the massive amount of misinformation on the web about oil companies and gasoline, comical in its breadth and detail, featuring a skepticism reserved for those industries that can be preceded by the word "Big" – as in Big Oil, Big Banking, Big Pharma. The relationship between them and the public is not just "We need you, but we don't really trust you," it is, "We need you, but we're suspicious of everything you say, especially if you're trying to get us to buy something more expensive. Then we know you're lying, you [expletive] [expletive] [expletive]."

It wasn't the trip we expected to take, nor is this the article we expected to write. Originally, all we expected to talk about was some of the technology and effort put into gasoline. But during our research, we realized that there is such wild mistrust of every oil company, including Shell, that we couldn't get straight to the explosive bits without explaining the purpose of gasoline detergents and additives.

So we've broken this story into two parts. Today's installment attempts to explain why gasoline not only makes your engine run but also coats intake valves and combustion chambers with carbon buildup, and dirties the motor oil. The second installment will address the push for additives that came with the mass introduction of fuel injected engines in the 1980s, the federal mandates for gasoline (all automotive gasoline, not just Shell's), the introduction of the Top Tier Gas designation and then the arrival of V-Power because of Shell's work with the Ferrari Formula One team.

Gas Prices Continue To Rise In California

This story came about because of Shell's invitation, so when we speak of a specific gasoline, we'll be referring to Shell's formulations and its V-Power. However, the facts about gasoline and its involvement in your engine's carbon buildup and cleaning can be found on the information pages of any gasoline maker, including Chevron, Exxon Mobil and BP. Every single one of those consumer resources says the same thing about how your engine gets fouled and what gas is designed to do, right up until the point where they say, "But our gas is better..."

Before we get to V-Power, let's clear up the marketing speak: V-Power is Shell's premium gasoline. Shell's Nitrogen Enriched Cleaning System is the detergent package in V-Power and every other Shell retail gasoline. While all Shell gasoline contains the Nitrogen Enriched Cleaning System, V-Power has the largest concentration of it compared to regular and mid-grade.

Next, let's look at how your engine gets dirty – and all engines get dirty inside. All of them. While we're doing that, we'll also look at whether all gas is the same, why gas has to do more than power your car (your engine, automakers and the government require it to do more) and why detergent additives like that found in V-Power – and Chevron's Techron and BP's Invigorate – are essential (because, remember, all engines get dirty inside). After all that, we'll get into what V-Power has to do with Ferrari F1.



So many enthusiasts believe that premium gasoline is a wicked cabal of the Seven Sisters bent on getting you to spend more at the pump. When it comes to fuels and your engine, the mistrust is abundant not only on internet forums, but in articles meant to explain the whats and whys of gasoline. A few examples:
  • A forum user says gas is "Probably all the same [censored]," and suggests that additives are just tracers so petroleum companies can track station owners
  • An article suspects nitrogen fuels are bad for your engine and are a way for fuel makers or station owners to dilute the fuel with water
  • A forum user advises another not to pay more for premium gasoline "unless the vehicle has around a 100,000 miles on it"
  • A forum thread begins with the question "Will my engine run better or worse if I clean carbon deposits?" The questioner thinks perhaps "the carbon has filled in any gaps and made a better seal where it was needed
Direct injected engines raise other issues. When people ask which brand of gas to use for a direct-injected engine, an answer like these are usually among the responses: "The intake valves never see the gas, so I don't think fuel quality makes much difference, and I'm not sure that diesel experience translates exactly to gas engine intake valve issues," and, "DI engines inject fuel into the cylinder, not into the intake port, so the intake valve buildup would be unaffected by gasoline grade. That said, I wouldn't suggest buying 87 octane at ARCO." That latter response was countered by a car company engineer, but you'd have had to click to page two to find it: "Cam overlap EGR means combustion deposits (and unburned fuel) still end up on the valves. Gasoline does matter."

And occasionally you'll run into a truly quizzical answer, like this one in response to a question about using an intake cleaner: "I suspect you never really need to do a cleaning regimen, and that it's not that effective. I do know from walking by a local place that does cleaning service: it pumps a lot of junk into the air." We've never met an engine that doesn't need to be cleaned, but if that were the case, where is that "local place" getting all that junk from?

Recently, on our own pages a commenter said in response to a Shell V-Power commercial in the video clip of a First Drive review, "Shell V-power Premium gas does nothing except drain more dollars from your wallet."





For that, Vicki Butler-Henderson at Fifth Gear has a rebuttal. In a segment called "Posh Petrol" from September 2012, a Volkswagen Golf was used to test four different brands of gasoline for any differences in horsepower. The Shell V-Power was good for a 4.8-bhp improvement over standard petrol.

But we're not here to talk about horsepower gains, nor to recommend any brand of gas. You should buy the gas that your car likes and that you want to buy. Just know that they're not all the same.

We're here to talk about engines and gas, the facts about what they are and the federally mandated standards that go into them.

One more time: all things get dirty, including the insides of engines. Think about it: engines are powered by the refined byproduct of rotted organic sludge dug out of the ground that's agitated to the point of explosions. That's going to make a mess. Or take it from a paper called "Carbon Deposit Formation from Thermal Stressing of Petroleum Fuels," prepared by two researchers at the Department of Energy and Geo-Environmental Engineering and The Energy Institute for the Argonne National Laboratory, which reads, "Almost all types of gasolines produce carbon deposits on engine components over time. The rate of deposit formation depends on the nature of metal surfaces in the fuel systems and gasoline additives used to inhibit solid deposition. Carbon deposits mainly build up on fuel injectors, intake valves and ports, and in the combustion chamber."

Dirty intake valves

Technology has gotten very good at cleaning up almost all of that mess, but even the self-cleaning oven isn't entirely self-cleaning, and ovens aren't powered by the refined byproduct of rotted organic sludge dug out of the ground and explosions. The cleaning help for your engine is gasoline, even though it's also that same gas that's getting your engine dirty in the first place.

Crude oil straight from the ground is, like humans, a funky bunch of organic compounds. Those compounds are broken down at the refinery into fuels and oils for various types of industries (automotive, aerospace, heavy, etc.) and feed stocks for other kinds of products. According to the American Petroleum Institute, a single 42-gallon barrel of oil can be refined into:
  • Gas for 280 miles for a car getting 17 mpg
  • Diesel fuel to get a semi 40 miles at 5 mpg
  • Enough asphalt for a gallon of patching tar
  • A quart of motor oil
  • Nearly 70 kWh of electricity
  • 12 14.1-ounce propane cylinders
  • 4 lbs of charcoal briquettes
  • Wax for 170 birthday candles or 27 wax crayons
  • Feed stocks for 39 polyester shirts, 750 pocket combs, 540 toothbrushes, 65 plastic dustbins, 23 toy hoops, 195 one-cup measuring cups, 11 plastic telephone housings and 135 four-inch rubber balls
The science of refining is intense, but it can only do so much, so there remain hundreds of different hydrocarbon compounds in the refined gasoline. Some of the products bind to the metal in the engine, some new compounds are formed during the combustion process and get left behind, and some of the heavier compounds get left behind in injector tips when fuel residue cools down after the engine is shut off. These are some of the reasons why detergent additives are necessary. (Gasoline contains other additives, too, like corrosion inhibitors and friction reducers, but that's for another story.)



Carbon buildup forms on the intake valves, pistons, rings and cylinder walls and alters the combustion process in all kinds of ways depending on where it is, and depending on what kind of deposit it is – the composition of intake valve deposits is different than that in the injectors, which is different to that on the cylinder walls. The deposits in the chamber, for instance, can raise the temperature inside the cylinder, leading to premature detonation because of adjustments made by the antiknock sensor that could require the use of higher octane gas to address. In extreme cases, there can be combustion chamber deposit interference between the piston and the intake valves at top dead center when the engine is cold.

Fuel injector deposits are thought to form during the heat soak period after the engine has been turned off, when the residual heat degrades the fuel as it cools and heavier carbon deposits are left behind. They clog the injector nozzles, reducing the amount of fuel that makes it into the cylinder, or they can affect the combustion process because of the change in the spray pattern.

Intake valves and ports are more subject to deposit buildup than fuel injectors because the valves operate at higher temperatures, and numerous sources say deposits can form in as little as a few thousand miles. Deposits on the intake valves restrict the flow of air and fuel into the chamber and change how fuel enters the cylinder, which can lead to the fuel not being vaporized properly and then getting sucked out of the cylinder before it's been burned, which can raise the emissions at the tailpipe and cause failure at a smog check. Intake valve buildup can also absorb fuel meant to go into the cylinders, so the car runs leaner than it's meant to – the carbon sponges up the gas – and that means less power. Other valve deposit problems include valves sticking in very cold weather because the valve stem has trouble sliding in its guide, and burned valves because they can't seat properly and feel the effects of combustion in the chamber.



Your engine wasn't designed to have random, small fires burning in it.

To demonstrate what spongy carbon buildup does inside an engine, a Shell engineer took a valve with carbon deposits and one without, dipped them each in a beaker of gasoline and set them on fire. The valve with the deposits not only absorbed more of the gasoline in its beaker, the deposits caught on fire and burned for a while. The clean valve burned up the gas and then the fire went out. And in case you didn't know, your engine wasn't designed to have random, small fires burning in it.

Systems meant to ensure proper engine function can also contribute to the formation of deposits. Positive Crankcase Ventilation (PCV) keeps the crankcase from filling up with blowby, which is the air and leftover combustion material that gets forced by the piston rings and down into the crankcase during combustion. PCV sucks in air from the intake system, then channels it through the case and back up into the intake system where it is re-fed into the cylinders. A side effect is that the carbon byproducts of combustion, along with tiny bits of oil, are blown through the intake system.

Components added to the engine to reduce emissions are also responsible for getting the engine dirty. Exhaust Gas Recirculation (EGR) was designed to reduce the temperature of exhaust gases in order to decrease the NOX that exits the tailpipe. The EGR does this by siphoning some off gasses from the exhaust manifold and rerouting them to the intake manifold to reenter the combustion process a second time. That means the effects of combustion are being sent back through the intake, all over the intake components, where they can stick to the oily film left over from the PCV system. It is a process about which YouTube user Dead Ballo said, "EGR: System to make your engine [censored] where it eats."



Shell techs had set up a fiber optic camera, or borescope, that allowed us to view the intake system of the 4.6L V8 engine in an employee's Lexus GX. It had been run exclusively on Shell V-Power gasoline for several thousand miles, and as you might expect – we were at the Shell Technology Center, after all – the intake valves looked to be rather clean.

But hey, it should be clear by now that something has got to clean that [censored] up. In Part 2, we'll explain how BMW, the Environmental Protection Agency, and top-tier gasolines are working harder to do just that.