🔍 Key Concepts

• Effect of mixing diesel fuel with lube oil on viscosity (thickness) of the oil • Meaning of octane number vs cetane number and which one applies to diesel engines • How contamination might affect pump discharge pressure in a lube oil system

💭 Think About

• If a thin liquid (diesel) is mixed with a thicker liquid (lube oil), what happens to the overall viscosity? • Are octane numbers used to rate gasoline or diesel fuel? Are cetane numbers used for gasoline or diesel fuel? • If the lube oil becomes thinner, would the pump have an easier or harder time moving it, and how might that affect discharge pressure?

✅ Before You Answer

• Verify which property (viscosity or pump discharge pressure) would change first and most noticeably when lube oil is diluted with diesel • Confirm whether octane or cetane is the correct rating term for diesel fuel quality • Ensure the chosen option directly reflects the physical effect of a lighter fuel contaminating a heavier lubricating oil