Disclosed herein is a method for preparing a piston-driven engine blended aviation gasoline composition. Blendstock for automotive gasoline containing an oxygen content in an amount that ranges from 0% by weight to 5.0% by weight and a lead content in an amount that ranges from 0 grams per gallon to 0.05 grams per gallon is blended with an octane enhancer and a pressurant, thereby making the piston-driven engine blended aviation gasoline composition. No additional amount of oxygenate or lead is added to the provided blendstock for automotive gasoline, and the method does not include a step of adding an additional amount of oxygenate or lead to the piston-driven engine blended aviation gasoline composition.

Disclosed herein is a method for preparing a blended gasoline composition comprising: a) providing an automotive gasoline; and b) blending the automotive gasoline with an octane enhancer and with a pressurant, thereby making the blended gasoline composition; wherein the blended gasoline composition comprises an oxygen content, contributed by ethanol, in an amount that ranges from 0% by weight to 0.75% by weight, based on the total weight of the blended gasoline composition and the total oxygen content weight contribution of ethanol present in the blended gasoline composition; wherein the blended gasoline composition comprises an oxygen content, contributed by methanol, in an amount that ranges from 0% by weight to 0.1% by weight, based on the total weight of the blended gasoline composition and the total oxygen content weight contribution of methanol present in the blended gasoline composition; and wherein the blended gasoline composition comprises lead in an amount that ranges from 0 grams per gallon to 0.05 grams per gallon of the blended fuel composition. Also disclosed herein is the blended gasoline composition.

An aviation gasoline composition having: from about 70 vol % to about 80 vol % isooctane; from about 5 vol % to about 9 vol % isopentane; from about 10 vol % to about 20 vol % of one or more dialkyl ether; and from about 1 vol % to about 5 vol % of one or more alcohol, from about 0.02 vol % to about 0.07 vol % of one or more octane enhancer such as MMT, and, optionally, one or more additives selected from the group consisting of: antioxidants, anti-icing agents, antistatic additives, corrosion inhibitors, dyes, lubricants, and mixtures thereof, wherein the aviation gasoline has a motor octane number of at least 99.6.

A fuel additive composition comprises (a) a Mannich reaction product and (b) a polyetheramine where the weight ratio on an actives basis of component (a) to component (b) is 1:4-10. A fuel composition and a method for removing intake valve deposits and combustion chamber deposits in a spark-ignited internal combustion engine comprise the fuel additive composition which is very effective in removing the deposits.