Gasoline Quality is more than just the Octane Rating

All gasoline starts out the same, regulations are intended to ensure minimal quality standards, and that is where most brands of gasoline start out. After that, it is up to the manufactures to enhance their gasoline with their own special ingredients to provide additional benefits. Additionally different grades of the same brand will have more additives.

During the 1980s significant problems with deposits accumulating on intake valve surfaces occurred as new fuel injections systems were introduced. These intake valve deposits (IVD) were different to the injector deposits, in part because the valve can reach 300 degrees C. Gasoline factors that cause deposits are the presence of alcohols or olefins. Gasoline manufacturers now routinely use additives that prevent IVD and also maintain the cleanliness of injectors.

Texaco demonstrated that a well-formulated package could improve fuel economy, reduce NOx emissions, and restore engine performance preventing and even removing existing engine deposits without adversely affecting performance. Most suppliers of quality gasoline will formulate similar additives into their products, and cheaper lines are less likely to have such additives added.
Some of the gasoline in our area that meet these qualifications are Chevron, Texaco and Shell. Read on for more insight in this.

Clean Gasoline
TOP TIER Detergent Gasoline is a quality standard for gasoline performance. Four of the world's top automakers, BMW, General Motors, Honda, and Toyota recognize that the current EPA minimum detergent requirements do not go far enough to ensure optimal engine performance.

Since the minimum additive performance standards were first established by EPA in 1995, most gasoline marketers have actually reduced the concentration level of detergent additive in their gasoline by up to 50%. As a result, the ability of a vehicle to maintain stringent Tier 2 emission standards have been hampered, leading to engine deposits which can have a big impact on in-use emissions and driver satisfaction.

These automakers have raised the bar. TOP TIER Detergent Gasoline help drivers avoid lower quality gasoline which can leave deposits on critical engine parts, which reduces engine performance. That's something both drivers and automakers want to avoid.
For more information and fuels that are Top Tier, Visit:

Fuel Additives
Gasoline additives such as de-icers or octane boosters usually do more harm than good. They contain alcohol which changes the volatility of the gasoline and may result in performance or hard starting problems. Although gasoline de-icer may be helpful when a small amount of water is introduced into the fuel, this condition is very rare under normal driving conditions when using quality fuel because of the sealed fuel systems on cars built in the last 20 years.

Fuel system cleaning additives can in some cases remove gum from the fuel tank and flush it into the injectors causing even more problems. Higher grade fuels contain detergents that will keep injectors, valves and fuel system clean if used regularly.

In the long run it is more economical to buy quality fuel to begin with, instead of trying to add expensive additives to accomplish what your fuel should be doing for you in the first place.

Why are there seasonal changes in Gasoline?
Only gaseous hydrocarbons burn, consequently if the air is cold, then the fuel has to be very volatile. But when summer comes, a volatile fuel can boil and cause vapor lock, as well as producing high levels of evaporative emissions. The solution was to adjust the volatility of the fuel according to altitude and ambient temperature. The oil companies without informing the public of the changes have automatically performed this volatility change for decades. It is one reason why storage of gasoline through seasons is not a good idea. Gasoline volatility is being reduced as modern engines, with their fuel injection and management systems, can automatically compensate for some of the changes in ambient conditions - such as altitude and air temperature, resulting in acceptable driveability using less volatile fuel.

Why is my Gas Mileage worse in the winter?
Two big factors can cause your gas mileage to be worse in the winter.
The first is temperature; the colder the engine temperature, the more fuel it needs. With a colder engine when starting and longer warm up time, more fuel will be used than in the same trip in the summer. This is especially noticeable in short trip driving.
The second is the season blend. Summer fuel has a higher energy content than the winter blend. Winter grades are made more volatile (less dense) to aid in cold start and warm up performance and typically contain 108,500 to 114,000 btu/gallon. Summer grades are of much lower volatility to minimize evaporative emissions and hot start/hot driveability problems. Summer grades will typically contain 113,000 to 117,000 btu/gallons. So the energy content, and therefore the fuel economy, can vary 3.4% to 5.0% just based on the energy content of the fuel.
The lower energy content of winter fuels and the other wintertime influences on fuel economy can easily lead to reductions of 10-20% in miles per gallon during the coldest winter months.

Yes, Gasoline does have an expiration date. When gasoline is stored, gums will form, the result of copper-catalyzed reactions of the hydrocarbons. Antioxidants and metal deactivators are added to slow this down, but after six months the fuel has degraded enough to be no longer good for use. Another problem with gasoline aging, is many of the performance and octane additives such as aromatic hydrocarbons evaporate and leave a fuel that delivers less performance than fresh fuel.
Ethanol fuel has a very short shelf life compared to straight gasoline.

Why do we need Octane Ratings?
To obtain the maximum energy from the gasoline, the compressed fuel/air mixture inside the combustion chamber needs to burn evenly, moving out from the spark plug until all the fuel is consumed. This would deliver an optimum power stroke. Detonation or knocking is caused by auto ignition in the combustion chamber before the flame front arrives.

If auto-ignition occurs, it results in an extremely rapid pressure rise, as both the desired spark-initiated flame front, and the undesired auto-ignited end gas flames are expanding. The combined pressure peak arrives slightly ahead of the normal operating pressure peak, leading to a loss of power and high cylinder temperatures. The unexpected pressure waves are superimposed on the main pressure wave, leading to a sawtooth pattern of pressure oscillations that create the "knocking" sound.

Different types of additives are mixed into gasoline at the refinery to boost octane levels. Cheaper fuels rely mostly on ethanol alcohol which will stop detonation or pinging but also affects performance.

Is Engine knock or ping harmful?
Yes, it can be very harmful. The combination of intense pressure waves and resulting high cylinder temperature can induce piston or ring failure. Under high-speed or high load conditions knock can lead to pre-ignition (pinging), which then accelerates engine destruction. Pre-ignition and detonation are the major cause of headgasket failures.
Major causes of pinging or detonation in the engine are:

1. Poor fuel quality

2. High cylinder temperatures caused by lean fuel mixtures, failed or mis-adjusted engine controls or high engine temperatures caused from cooling system problems.

3. Carbon build-up in the cylinders.

4. Malfunctioning EGR system or fuel related sensor.

History of Gasoline
In the late 19th Century the most suitable fuels for the automobile were coal tar distillates and the lighter fractions from the distillation of crude oil. During the early 20th Century the oil companies were producing gasoline as a simple distillate from petroleum, but the automotive engines were rapidly being improved and required a more suitable fuel. Early fuels would "knock" and crack the cylinder head or pistons.

It was found that the knock was caused by a rapid rise in pressure after ignition, not during pre-ignition as believed. This then lead to the long search for anti-knock agents, culminating in tetra ethyl lead. Typical mid-1920s gasoline was 40 - 60 Octane.

The 1950s saw the start of the increase of the compression ratio, requiring higher octane fuels. Lead levels were increased, and some new refining processes, specifically designed to provide hydrocarbons components with good lead response and octane, were introduced. Minor improvements were made to gasoline formulations to improve yields and octane until the 1970s - when unleaded fuels were introduced to protect the exhaust catalysts that were also being introduced for environmental reasons. From 1970 until 1990 gasolines were slowly changed as lead was phased out. In 1990 the Clean Air Act started forcing major compositional changes on gasoline, and these changes will continue into the 21st Century because gasoline is a major pollution source.

What are the hydrocarbons in gasoline?
Hydrocarbons ( HCs ) are any molecules that just contain hydrogen and carbon. They are used to control the boiling or volatility point, which along with other additives determines the octane level. Gasoline contains over 500 hydrocarbons that may have between 3 to 12 carbons.

Fuel Pump Care:
GAS TANKS should be kept at least 1/4 full if your vehicle has fuel injection. This keeps plenty of fuel for the electric pump, which depends on a constant supply to cool and lubricate its internal parts. Running low on fuel causes the pump to wear out more quickly. Dirty fuel filters can also cause early pump failure from overheating.