🔍 Key Concepts

• viscosity and what makes a fluid thinner vs thicker • how adding a lighter fuel (diesel) affects lube oil properties • relationship between flash point/pour point and contamination with lighter fractions

💭 Think About

• If you mix a thick oil with a much lighter fuel, what happens to how easily it flows at normal temperatures? • Would adding diesel (which ignites more easily than lube oil) make the mixture’s flash point higher or lower? • Think about which property would change most obviously and be easiest to detect when checking oil condition on board.

✅ Before You Answer

• Compare the typical viscosity of clean lube oil versus diesel fuel oil • Recall whether diesel fuel has a higher or lower flash point than lube oil • Consider whether contamination with a lighter fuel would raise or lower the pour point of the lubricant