Pump Fuel Conversation Continued

[Lt.Stryker]

Brad Hibbard has previously written on the varying water levels in pump fuel, and he's right. Condensation occurs in the holding tanks and 4 - 6% of the fuel in the holding tank is actually water. When you get above the 6% range you'll see the affects in your street rod -- typically the hesitation between when you press the accelerator and your car responds. Water has a higher volumetric density than does gasoline and sits in the bottom of the tank. (Gas has a density of ~0.6 g/mL compared to 1 g/mL for water.) I'll get to the significance of that in a moment, but first... Pump fuel also contains additives, detergents and in many cases ethanol. The fuel additives are supposed to prolong the lifespan of the fuel and reduce the lacquering affect (old, stagnate fuel turns into a paste and clogs carbs and fuel injectors). The purpose of the detergents is to meet emissions standards and limit injector and intake valve deposits (carbon build up). The EPA sets the minimum standards for the detergent levels but many oil companies choose to exceed the minimum standards by up to 120% of what's legally required in part because the additives/detergents are cheaper than the fossil fuel; the downside to the detergents is they have a different combustion ratio from the fuel itself causing the motor to run leaner (ie., the higher the additive/detergent content the leaner the motor runs). Most people recognize that ethanol is a made from corn and introduced in pump fuel to slow National fossil fuel consumption, but what most don't realize is that it's in the alcohol family. It's the alcohol PH properties that affects the seals, gaskets, and basically any rubber/silicone surface in your motor. That's why two stroke/four stroke engine manufacturers (Outboard Motors Manufacturers -- ie., Evinrude) do not recommend using ethanol. And now back to the gas station delivery dynamic... When an OTR tanker delivers fuel to your local gas station they dump fuel into the holding tank and in so doing oxygenate (pro) and agitate (con) the fuel. On the upside, oxygenated fuel burns hotter and more efficiently. The downside is that the fuel is agitated and it re-mixes the water into the fuel mass and it also stirs up the sediments sitting on the bottom of the holding tank. In a street car the pros and cons are a wash -- they negate each other. But, in a race car which is built to more exacting standards with much smaller tolerances there's a noticeable difference behind the steering wheel and it's very likely based on the higher water content, the additives, the detergents, and the ethanol that you'll reduce the lifespan of your motor. The Shell and Texaco refineries have the most stringent additive/detergent standards while Coastal, British Petroleum (BP), and Lukoil (a Russian owned refinery) have the lowest. In other words, if you inclined or forced to use pump gas because of a restricted racing budget then stick with Shell or Texaco and don't fill up when there's a tanker delivering fuel to the gas station. I'd also avoid mom and pop gas stations unless you know the refinery where they purchase they fuel from.

[dirtdobberrr]

I am a fuel delivery driver in SouthEast Alabama. I will say this, the moisture content in e10 gasoline that u buy at your local station is almost always less than 1%. Any condensation that forms inside the tank is absorbed by the fuel when the tank is refilled. If a tank has a much higher than 1% moisture content, the tank almost always has to have a rainwater intrusion problem. Having said that, I refuse to use e10 gasoline in ANYTHING other than my on road vehicles. Ethanol is known to degrade rubber seals in our fuel systems. I can attest to this because it shrinks the rubber seals that we fuel haulers use in our unloading hoses. Before we started handling e10, these rubber seals would last until the act of coupling them to the trailer eventually tore a hole in the seals. But now that we hall e10, the seals last about 3 months, and then they start to harden up and shrink. To address what was said about any certain brand of gas being "better" than any other brand, this is simply not true(if u are talking about simply octane). There may only be one or two terminals that supply most of the fuel for any certain area. Most gas terminals sell several brands of gas, and they also sell unbranded fuel. The unbranded and branded fuel comes out of the same tank. The branded gas is loaded with a certain amount of the aditive that the buyers wants. The unbranded fuel usually has much less additve, maybe as little as 10% the additive that branded gas has. I do believe that some additives cause more detonation problems than others, but I cannot prove this.