Sparker, methanol is a form of alcohol, made from wood, and is not a petrochemical. It has been used as an antifreeze, but is not a good one and is not what you normally get when you buy antifreeze. Methanol is highly toxic and causes very nasty failure modes of the human body, notably blindness. Naptha is a petrochemical, made from crude oil. Naptha, historically called Shellite in Australia and "white gas" in the US, is used as a fuel for camp stoves, a solvent, and can also be used as a component of petrol. It does not vaporise as easily as petrol, which is sometimes useful - but some versions of naptha are carcinogenic.
The ususal antifreeze is neither methanol nor naptha: it is ethylene glycol, and is both sweet, and highly toxic. Never, ever drink automotive coolant, and keep it away from children (who tend to like the taste).
Of the three items, the only one I would ever use for engine-related cleaning is naptha (Shellite), but it is no better for the purpose than petrol. Simple alcohols like methanol can be useful solvents for some purposes - it is an alternative to methylated spirits (or denatured alcohol to Americans) - but for engine-related purposes it is not very effective. I've never heard of anyone using glycol as a cleaning agent - it is a thin, slimy liquid that mixes readily with water.
Remember that every material I have mentioned is toxic and dangerous.
