An oil container labeled 10W-30 is given which rating when tested at -18°C?

An oil container labeled 10W-30 is given which rating when tested at -18°C?

• A. SAE 10
• B. SAE 30
• C. SAE 5
• D. SAE 15

Answer: (A)

The winter (W) part of the multi-grade label tells you how the oil behaves at cold temperatures. The first number before the W—10 in 10W-30—is the cold-temperature viscosity rating. When tested at a cold temperature like -18°C, this oil behaves like a 10W oil, meaning it remains fluid enough to start and lubricate on startup. The second number (30) describes its viscosity when hot, around engine operating temperature. So at -18°C, the rating you’d use is SAE 10 (the winter grade). The other options refer to different cold or hot viscosities, which don’t apply to this test temperature.

The winter (W) part of the multi-grade label tells you how the oil behaves at cold temperatures. The first number before the W—10 in 10W-30—is the cold-temperature viscosity rating. When tested at a cold temperature like -18°C, this oil behaves like a 10W oil, meaning it remains fluid enough to start and lubricate on startup. The second number (30) describes its viscosity when hot, around engine operating temperature. So at -18°C, the rating you’d use is SAE 10 (the winter grade). The other options refer to different cold or hot viscosities, which don’t apply to this test temperature.