Will using a higher octane fuel increase the car's miles-per-gallon rate?

Answer 1

YES! It depends upon the car. Most typical vehicles don't improve mileage when running a higher octane gas. They don't have enough compression to justify the higher octane. Even in the rare cases a car does get better mileage than it might on lower octane, the improvement doesn't justify the cost. Some performance cars benefit from higher octane fuels. The realized benefit isn't better mileage; it's better power. For lots of great information, read the original Gasoline FAQ: http://www.faqs.org/faqs/autos/gasoline-faq/ It will neither increase your mileage nor your power. High-octane fuel is simply a cleaner version of the hydrocrabons used in regular unleaded fuel. It cuts down on the knocking because it is more resistant to self-ingnition. And knocking as many unfortunate people have found out, damages your engine. However, not all cars are able to handle high-octane fuels. Typically, cars made before 1986 are not equipped to run on high-octane fuel. Owners should check with their local dealer or manufacturer before using high-octane, or premium fuel, in their cars made before 1986. For most cars the answer is NO. Higher octane fuels burn slower so unless you can increase your initial advance you will not see any difference. Also when a vehicle is tuned to use lower octane fuel a higher octane will create carbon deposits and over time will cause engine ware, overheating, and poorer fuel economy. Todays igitions are computer controled many are distributorless so we shade tree mechanics can't mess with them. Many of todays vehicles recommend 91 octane but can use 89 or 87 if you don't hot rod them or over load them, more than two people. No, just the opposite. Lower octane fuels, say 87 pctane, have more hydrocarbons than higher octane fuels, say 91 octane, because the higher octane fuels have had non-hydrocarbon additives put in that reduce the capability to have the highest "burn" otherwise possible. The higher octanes are for cars with high compression engines and they are there to prevent knocking, which can damage the engine. This information is taken from the American Petroleum Institure website