Important to note that Wildcat EXTRA has 18% oil; if it doesn't say EXTRA on the side of the label, vertically, then it only has 16%.

I buy bottles of castor from Price Chopper; $2.75 for 6oz, and a half bottle to a gallon will bring the oil content up over the 1% you need.

Wildcat Extra 10% is a great fuel - enough power, enough oil, and less expensive than 15%. The only thing I noticed about using 15% nitro is how much faster I burned fuel (have to open needle valve to let more fuel in).