The discussion focuses on finding effective non-polar hydrocarbon solvents that can dissolve carbon particles and tar without damaging steel alloys. Non-polar solvents, such as those found in products like WD-40, brake cleaners, and engine degreasers, are highlighted for their ability to efficiently remove dirt and carbon buildup, particularly from spark plugs after extensive engine use. The conversation emphasizes the importance of selecting a solvent that balances speed and ease of use while ensuring compatibility with metal components. References to specific solvents like Stoddard solvent and mineral oil suggest potential options for achieving effective cleaning without adverse effects on alloys.