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Dear tjts1,
May this find you well. A key difference between gasoline grades is the amount of detergents/gallon: the government only sets a minimum level.
These chemicals keep fuel system surfaces from being coated with performance-degrading paraffins (waxes) and their carbon-rich combustion residues. These performance-degrading chemicals and residues vary widely for the same brand over time.As detergents are expensive to produce, manufacturers add more to the higher-priced grades of gasoline, and boost the price accordingly.
While we think of chemical products as being pure - i.e., household bleach has 5-6% sodium hypochlorite and 94-95% water (and nothing else) - gasolines are chemical cocktails. Their key commonality is the octane rating.
The octane rating of a gasoline tells us its knock resistance, or how smoothly it burns. The octane number is based on a comparison of isooctane (2,2,4-trimethylpentane) and heptane. If isooctane gets a rating of 100, because it burns smoothly, then heptane gets an octane rating of 0, because it knocks badly.
Gasolines contain a variety of hydrocarbon molecules: most are alkanes with 4-10 carbon atoms per molecule. Gasolines also contain smaller amounts of aromatic compounds (aromatics are ring-shaped compounds, e.g. toluene), alkenes and alkynes.
In short, when we buy gasoline, we're buying a product, with widely varying contents. These will depend on the nature of the raw material. Crude oils vary widely in terms of their content of sulfur, paraffins, metals, etc., and refineries accordingly can process limited ranges of crudes. Most of these compounds will be removed by refining.
Thus, while the car may run fine on a lower octane fuel, the lower amounts of detergents/gallon in regular versus premium likely mean a slow build-up of these residues on fuel system working surfaces.
The way to combat this build-up - which can degrade injector performance among other impacts - is to add detergents. Techron - and similar products - remove gasoline residues, and keep clean fuel system component working surfaces (pumps, injectors, fuel pressure regulator, valves, pistons, etc.)
In short, feel free to save money on gasoline - so long as it does not degrade engine performance - but do not neglect to give back some of your savings to your car, in the form of additional detergent.
Add the detergent to the tank before you fuel, once every 1,500 miles or so.
Over 100K miles, a 12 oz bottle of Techron @ $5.99, will cost about $400. If the cost of premium gasoline over regular is $1,000, you're still $600 ahead. Y
Recent posts show how hard it is to change fuel pumps. Thus, the money spent on extra gasoline detergency would seem to me to be money well spent. It will save you on parts, time, frustration, skinned knuckles, etc., etc. Sounds like a good trade.
Yours faithfully,
spook
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