Red Line's synthetic motor oils are designed to provide the highest protection, cleanliness and superior drain intervals with the lowest friction for your gasoline, diesel, motorcycle or marine engine. Red Line uses the most stable components available and formulate their products for wear protection and friction reduction across a wide range of engine operating conditions. Red Line's products are unique because they contain polyol ester base stocks, the only lubricants which can withstand the tremendous heat. The Red Line 10W40 is the 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.