Adding methanol (paint thinner) and lye (drain cleaner) to vegetable oil will produce diesel fuel–called biodiesel–but of exceedingly poor quality. Producing something you would want to put in an engine requires high-quality ingredients and precise measuring. Several communities exist online (see References and Resources below) to guide beginner diesel fuel brewers.
Pour the methanol into the 1/2-liter container using a funnel. The lye can be potassium (KOH) or sodium (NaOH) hydroxide. This recipe uses KOH. Measure it according to its purity: 5.8 grams for 85 percent pure, 5.5 grams for 90 percent, 5.3 grams for 92 percent. Pour the lye into the container using a clean funnel. Swirl the container until the mixture is clear. The result is methoxide.
Test the quality of the fuel. Pour 1/2 liter of water into it. Shake vigorously. Let it settle. If the fuel completely separates from the water within 30 minutes, it's good. Decant the fuel from the water into a clean soda bottle. But if it continues to look like mayonnaise, start over with more-precise measurements.