If an engine lubricating oils viscosity is given as SAE 20W as compared to SAE 20, what is the significant difference between the two lubricating oils?

Correct Answer: Option B — The SAE 20W oil is primarily intended for low ambient temperature service, and the SAE 20 oil is primarily intended for high ambient temperature service.

SAE viscosity ratings follow SAE J300 standards. The 'W' suffix denotes winter-grade oils, specifically tested for low-temperature cranking and pumping performance. Conversely, non-W oils are formulated for standard operating temperatures. Therefore, SAE 20W is optimized for cold starts, while SAE 20 is intended for higher ambient temperature service conditions.