Mon Prof Augmenté
Oil in Fuel or Separate Oil
Age 18 · Environmental Science
A two-stroke engine lubricates by mixing oil into the fuel, so some oil burns poorly and leaves in the exhaust. A four-stroke engine keeps oil in a separate reservoir, so it produces less smoke, less pollution, and wastes less fuel.
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In the picture
- Transparent fuel canister: amber fuel with dark oil streaks mixed together
- Exhaust pipe plume: dense blue-grey smoke carrying oily droplets
- Separate oil reservoir: clear lubricating oil held apart from the fuel
- Second exhaust pipe: faint pale exhaust with little visible smoke
Examples
- String trimmers and chainsaws often use two-stroke engines and require oil to be mixed into the fuel can.
- Most cars use four-stroke engines with a separate oil sump and produce less visible exhaust.
Key takeaways
- Two-stroke engines mix oil with fuel, so some lubricant leaves with the exhaust.
- Separate lubrication in four-stroke engines reduces smoke, pollution, and fuel waste.
Quiz: Oil in Fuel or Separate Oil (Age 18)
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What happens to some of the lubricating oil in a two-stroke engine?
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How does a four-stroke engine keep its lubricating oil?
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What is an advantage of four-stroke separate lubrication over two-stroke oil-in-fuel?
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