How Engines that use Gas/Oil mixtures don’t self destruct

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My knowledge is regular car engines. On a typical combustion engine, you don’t want oil spraying or leaking into the combustion chamber as you would develop carbon deposits and degradation of performance.

How do these mix engines work both from a function aspect (lubricating via the gas) and maintenance (not building up catastrophic amounts of carbon)?

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Anonymous 0 Comments

I think you are talking about two stroke gas engines here. These do not have a lubricating oil system but instead use the fuel air mixture to lubricate the engine. Gasoline is too “dry” to be used as lubricant which is why you add lubricating oil to the fuel. This does mean that lubricating oil does get into the combustion chamber. But the engine is tuned for this. In order to avoid carbon buildup the fuel air mixture have more air. The carbon will therefore burn in the extra oxygen rather then build up. But in general oil does not burn very well and you do end up with a smelly blue exhaust rather then the transparent clean exhaust from normal engines.

You do also see fuel being used as a lubricant in diesel engines. Specifically in the fuel pump and injectors. But diesel is thick enough that it can act as a useful lubricant if the parts are built with the tolerances for it. This is why diesel engines will not run on gas, but from experience they do handle the mix of gas and lubricating oil you use in two stroke gas engines.

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