While Red Line Synthetic Engine Oils are derived from our Race Oils and are used by many racers, they were formulated specifically for street use in all kinds of passenger cars and light, medium and heavy trucks. Red Line Engine Oils outperform all petroleum-based oils and all other synthetics on the market today. Our Engine Oils are designed to provide highest performance, best durability, ultimate protection and outstanding cleanliness along with lowest friction to your automotive, motorcycle, marine or stationary engine running on gasoline, diesel, alcohol or natural gas fuel. At Red Line, we use the most stable synthetic lubricant base stocks available and formulate our products for wear protection and friction reduction across a wide range of engine operating conditions. Red Line lubricants are unique because they contain polyester base stocks, the only lubricant base stock type that withstands the incredible heat present in the hot sections of jet engines. This high-temperature stability makes Red Line Engine Oils a necessity for proper lubrication of high-performance engines, turbo-charged engines, heavily loaded truck engines or any engine that runs high engine oil temperature. Red Line is not just for high-performance and racing. Ordinary cars and trucks that see "daily driver" duty benefit greatly when their engines are lubricated with Red Line engine oils. More performance, better fuel economy and increased durability come with use of our oils in daily drivers. Because of the robust polyester base stock and high-performance anticorrosive additive package in Red Line oils, they are ideal for use in street-driven vehicles at extended drain intervals. Red Line recommends oil changes for engines that are in good condition and do not see frequent starts without warm-ups or short-trips at between 10,000 and 18,000 miles for gasoline engines, 10,000 and 12,000 miles for diesel engines, or every 12 months, whichever is shorter. Red Line 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.