5W30: Provides the quickest starts and fastest oil pressure rise. Will reduce turbo lag and provides more power and best economy in an engine in good condition. Replacement for OE factory-fill oils in passenger cars and most light trucks, including most new GM cars and trucks. Thicker oil film at operating temperature than a petroleum 10W-40. Best choice for engines operated in extreme cold weather.

10W30: Best all-weather viscosity grade for gasoline engines in cars and light trucks that are driven on the street on a daily basis. Reduces turbo lag and provides more power and economy while providing thicker bearing oil films at operating temperature than a petroleum 10W-40. Best all-round, synthetic oil for stock or slightly modified engines in high-performance cars that are street-driven. Best choice to replace a 5W-30 or 10W-30, petroleum-based or other-brand synthetic oil if maximum durability is preferred. Acceptable for engines that are occasionally operated in extreme cold weather.

10W40: Best choice for engines that typically run high oil temperature or for engines in daily-driven vehicles regularly operated in hot weather. Great for medium and heavy duty gasoline engines in trucks. Best choice for high-performance engines that see street/strip or track activity. Features a thicker oil film at operating temperature than a petro-based 20W-50.

5W20: The lightest multigrade street engine oil Red Line makes. Replacement for OE factory-fill oils in many new Ford and Honda passenger cars and light trucks. Excellent performance in weather where cold starting and short running duration are concerns.

20W50: Red Line's highest temperature protection engine oils recommended for street use. Excellent for engines that run large clearances such as air-cooled engines or large-displacement, all-out racing engines that see occasional street use. Red Line 20W50 provides 25% more viscosity in bearings than petroleum based 20W50 oils. Red Line does not recommended 20W50 for use in extremely cold climates. It is also not suggested for street use in production engines that see sustained oil temperatures below 225F (those engines should use Red Line 10W30 or 10W40).